Thanks.
I just realized that I had been so used to my instructor's problems where he provides the prices for each product that I had no idea what to do when he doesn't give any prices.
(It works on problems which are similar to the one I just asked for.)
[SOLVED] Managerial Economics Problem
SOLVED
I already solved (a) by finding the derivative with respect to (x,y) and equating to 0.
(a) X* = 15, Y* = 20
My prof provided the answer to (b) and I have absolutely no idea to how he arrived at it.
I assumed the the Income(M)=31 but without any...