Just (c) and (d) please. Show all work

For each of the following constrained optimization problems, find the comparative-statics effects of a change in the a-variables, and derive and sketch the value functions: (a) max y = x0.25 0.75 subject to 2x1 + 4x2 = a (b) max y = 2x1 + 3x2 subject to alx, + 5x7 = 02 (c) max y = x1 0.25 0.75 X 2 subject to 2x- + 5x7 = a (d) miny = 2x1 + 4x2 subject to x 0.25 0.75 = a (e) max y = (x1 + 2) (x2 + 1) subject to x1 + x2 = a (f) min y = alx1 + x2 subject to (x1 + 2) (x2 + 1) = a2