You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
Economic_inequality

Context:
In Marxian analysis, capitalist firms increasingly substitute capital equipment for labor inputs (workers) under competitive pressure to reduce costs and maximize profits. Over the long-term, this trend increases the organic composition of capital, meaning that less workers are required in proportion to capital inputs, increasing unemployment (the "reserve army of labour"). This process exerts a downward pressure on wages. The substitution of capital equipment for labor (mechanization and automation) raises the productivity of each worker, resulting in a situation of relatively stagnant wages for the working class amidst rising levels of property income for the capitalist class.

Question:
What do capitalist firms substitute equipment for in a Marxian analysis?

labor inputs