Answer:
$6,400
Explanation:
The equilibrium income in the economy is calculated by dividing autonomous expenditures by the marginal propensity to expend (or marginal propensity to consume) = $3,200 / 0.5 = $6,400
Autonomous expenditure refers to aggregate expenditures that are not affected by the real income level, since these expenditures are necessary and virtually automatic. For example, government's autonomous expenditures include the salaries paid to government employees (they must be paid). Or a household's autonomous expenditures include utilities, mortgage, food (and other basic necessities).
