Justin has the utility function U= xy, with the marginal utilities MUx = yand MUy= x. The price of xis $2, the price of yis p_y, and his income is 40. When he maximizes utility subject to his budget constraint, he purchases 5 units of y.

1. What must be the price of yand the amount of xconsumed?
2. Prove that this allocation follows the equi-marginal principle
3. What would be the new bundles of x, y if Px was $3