What's the meaning of "marginal propensity to consume"

What's the meaning of "marginal propensity to consume" 一道宏观经济题,给定MPC（marginal propensity of consume）= 0.75 what 's the meaning of. What's the meaning of '@'? what's the meaning of Pets What's the meaning of "gou to the dogs"? What's meaning of "answer to the question" What’s the meaning of family according to you? What's the meaning of"Life speaks to our hearts." what's the meaning of the CJ? What's the meaning of the sentence? 翻译一句英语句子marginal propensities to consume out of liquidity