Marginal propensity to import is the fraction of additional income spent on imports.
It is given that M = 60 + 0.06Y
Therefore, marginal propensity to import (m) = 0.06. It reflects induced imports; that is the part of the total imports, which is a function of income.
Since the marginal propensity to import negatively affects the aggregate demand function, when income increases the aggregate demand decreases. This is because the additional income is spent on foreign goods and not on domestic products.