Suppose C(x) measures an economy's personal consumption expenditure and x the personal income, both in billions of dollars. Then the following function measures the economy's savings corresponding to an income of x billion dollars.

Question

Suppose C(x) measures an economy's personal consumption expenditure and x the personal income, both in billions of dollars. Then the following function measures the economy's savings corresponding to an income of x billion dollars.
 S(x) = x - C(x)    (Income minus consumption) 
The quantity dS/dx below is called the marginal propensity to save.

For the following consumption function, find the marginal propensity to save. 
C(x) = 0.701x + 99.34 
$       billion per billion dollars

Reiny · Accepted Answer

according to your definition ... S(x) = x - .701x - 99.34 then dS(x)/dx = 1 - .701 = .299

some one · Answer

This is a optimization problem !!