I don't know how to solve a problem with the Edgeworth box. Can you solve this and provide in-depth information on how and why you are doing each step?

1) Suppose you are in a barter economy with 2 people(a and b) with 2 goods(x and y). The utility curve is given by Ua and Ub respectively to each consumer.

Ua=min(x,y/2)

Ub=ax+3y

a) Draw the Edgeworth box

b) Explain if consumer a has 40x and 80y is optimal. If not, find the optimal exchange spot.

c) Explain if consumer a has 60x and 80y is optimal. If not, find the optimal exchange spot.