Suppose Measures an Economy's Personal Consumption Expenditure and X

Short Answer

Suppose measures an economy's personal consumption expenditure and x the personal income, both in billions of dollars.Then, measures the economy's savings corresponding to an income of x billion dollars.Then .
The quantity dS/dx is called the marginal propensity to save.
For the consumption function find the marginal propensity to save.Round the answer to three decimal places, if necessary.
$__________ billion/billion dollars