Andy purchases only two goods, apples (a) and kumquats $(k) .$ He has an income of $\$ 40$ and can buy apples at $\$ 2$ per pound and kumquats at $\$ 4$ per pound. His utility function is $U(a, k)=3 a+5 k$ That is, his (constant) marginal utility for apples is 3 and his marginal utility for kumquats is $5 .$ What bundle of apples and kumquats should he purchase to maximize his utility? Why? A