explain how to use mental math to find an 18% tip for a meal that costs $25?
536129
Well, 18% is a little less than 20% and 20% is equal to 1/5. 1/5 of $25 is $5 so you could leave $4.75 or something like that.
811671
Everything is supposed to add up to $25 not $30. Think of it like this...\n\n$30 was paid to the manager. SO he has $30. HE took out $5 from this to give them back...so in essence he has $25 in his possession. \n\nThe three people paid $30 and were given back $3 ($1 EACH) Therefore they actually paid $30 - $3 = $27. The bellhop kept $2 which when subtracted from the $27 would give equate the $25 in the possession of the manager.\n\nThe trick in the question was adding back the $2 that the bellhop had, instead of subtracting.
698522
Let say you were to go to the resturant and their were 2 people were sitting and eating and they had to pay 100 dollars. they both want to spend a equal amount of money. What about this. They want to know how much lenght is something. You also use math when you have homeworkk or you playa insturment and you want to play a equal amount everyday but you can only hane a total of 7 days and 80 min you have to practice.
226757
5 cokes + 5 burgers = $18.40\n\nif you divide everything by 5 you get\n\n5/5 cokes + 5/5 burgers = 18.40/5 dollars\n\n1 coke + 1 burger = 3.68\n\nthere you have a common denominator, and can therefore divide both sides by the same number\n\nto find the price of each, you can use that figure with the second equation you were given: \n6 burgers + 3 cokes = 18.21\n\nwe know that 1 burger + 1 coke = $3.68\n\nso multiply both sides by 3\n\n3 burgers + 3 cokes = 3 * 3.68 = 11.04\n\nsubtract that from your final total:\n\n6 b + 3 c = 18.21\n3 b + 3 c = 11.04 (subract this from above)\n-------------------\n  3 b + 0 c =   7.17\n \ntherefore\n\n  3 b       =   7.17\n\ndivide both sides by 3 to get your answer: 1 burger  = $2.39\n\nthe trick is to find common denominators, and always multiply or divide both sides by the same number\n\n\n\nChecking your answer: we now know the price of one of each ($3.68) and of a burger only (2.39) so we can figure out the price of a burger \nboth - burger = coke\n3.68 - 2.39 = 1.29 \n\nso,\n\n5 cokes + 5 burgers ?= $18.40\n5 * 1.29+ 5 * 2.39  =\n6.45    + 11.95     =\n18.40 (seems correct)\n\nlet plug in again\n\n6 burgers + 3 cokes =? 18.21\n6 * 2.39  + 3 * 1.29 =\n14.34 + 3.87    = 18.21\n\nalways plug your answers back into the equation to make sure they are right.
429688
Or, if you need a single equation, let p = number of pizzas, and 500-p = number of hamburgers.  Then multiply each number by that item's cost and add to get 1300:\n\n2p + 3(500-p) = 1300\n\nUse distributive and go from there.
441515
times 2000 by %6.125 then divide by 2, thats added to the $2000, then multiply the new cash value by %6.125 and divide by 2, then repeat the process that i have gone through twice 2 more times\n\n%6.125 equals 0.06125
144179
Basically: There is an initial $30 charge.  It should have been $25, so $5 must be returned and accounted for.  $3 is given to the 3 friends, $2 is kept by the manager - there you have the $5.  \n\nThe trick to this riddle is that the addition and subtraction are done at the wrong times to misdirect your thinking - and quite successfully for most.  Each of the 3 friends did indeed pay $9, not $10, and as far as the friends are concerned, they paid $27 for the night.  But we know that the clerk will tell us that they were charged only $25 and when you add the $3 returned with the $2 kept by the bellhop, you come up with $30.
11288
Ask\nAnswer\nVote & rate\nRepeat.\n\nThat'll help you get to the 25,000 points that you need.
979142
Remember for numbers 0-4 you round down, for numbers 5-9 you round up. \nA. $90\nB. $4.56\nThese are just to explain. You can do the rest yourself. If you really don't get it speak to your mom, dad, or teacher, you need help.
269448
First turn the % into a decimal by moving the decimal point two places to the left.  \n20%=.2\n\nThen take .2 x 620.87 = $124.17\n\nFinally add that number to your original number\n$124.17 + $620.87 = $745.04\n\nThis process will work with different numbers.
64986
I always tip 20%. Unless the waitress is rude...in which case I put down 25 cents. I don't blame the waitress if the food is bad...but, I do expect them to be nice.
956860
Isn't it 25%?\n\nFirst you find the difference.\n32 - 24 = 8\nThen you divide the difference by the original price.\n8 / 32 = .25\nMultiply by 100.\n25%
1167216
I just did an economic study on this one...outside of general good service...\n\nIntroduce yourself BY NAME.\n\nWrite "Thanks, [your name]" on the check near the total of the bill.  In casual dining, a happy face helps!\n\nListen to your customers.  For some, be the life of the party.  For others, be calm, efficient, and polite.\n\n"Sell up".  Get the extra salad, drink, glass of wine, appetizer.\n\nExpensive restaurants will result in larger tips.  But sometimes that will be offset by fewer hours.  However, fine dining is still pays the most overall.
345970
Ok, I got it.  I recommend writing the numbers 1-12 and crossing them out as you use them.\n\nYou've got your 5,6,1,and 8 on the inside.  So on the upper row of four, 5+6=11, so you need 15 more to make 26.  The only numbers that are left where 2 add up to 15 are 12&3 or 11&4.  I tried 11&4 first and will just tell you it didn't work, so it's 12&3.  Now to decide which goes where.  If you put the 3 on the left, it lines up with the 1 making 4, and there's no other numbers that will add up to the required 22 - so 12 must go on the left and 3 on the right.\n\nNow you can see the line  from the bottom point up to the 3.  8+3=11, so you need 15 again, and the only choices left are the 11&4.  Put the 11 at the bottom point and the 4 between the 8&3.\n\nNow looking at the line that goes from 12 down to the 11 you have 12+1+11=24, so you must use the 2 here.  Now you have 7,9 & 10 left.\n\nLooking at the line with the 5&2, that makes 7, so you need 19.  The only way to get that is with the 10 & 9, but you don't know which goes where.  You DO know, though, that the only other point that is left gets the 7.  That's the bottom right point.\n\nThis made a line with 7,6,4 and the very top point.  7+6+4=17, so you need 9 at the top to make 26, which leaves the space for the 10 at the bottom left.\n\nIn order, from top to bottom/left to right you have\n\n9\n12,5,6,3\n2,4\n10,1,8,7\n11
436681
22/0.88 = 25\n\nto get from 25 to 22 you mulitply by 0.88 (100% - 12% = 1-0.12 = 0.88)\n\ntherefore to go the other way you divide by the 0.88
319991
because the analogy at the end is incorrect. the 2 dollars that the waitress had is part of the 27 dollars that the guys paid. if you look at it from a different  and correct perspective, the guys paid $27 each and kept 3. Or, now the waitress has 27 dollars thand the guys have three
623311
Hi,\nThe easiest way that I calculate 20% from any amount is to take any given amount and divide by 5.  Example:  $25.00 divided by 5 equals $5.00.  This formula ALWAYS works.  good luck.  I know you can do this!