Find the maximum and minimum values of the objective function f(x, y) and for what values of x and y they occur, subject to the given constraints.
f(x, y) = 10x + 4y
x ≥ 0
y ≥ 0
2x + 10y ≤ 100
9x + y ≤ 54

a. max at (5,9)=69, min at (0,0)=0
b. max at (6,12)= 108, min at (0,0)=0
c. max at (0,10)=40, min at (0,0)=0
d. max at (6,0)=60, min at (0,0)=0

D. is not the answer