Question 1085167
*[illustration 337.JPG].
Check the value of the function at each of the vertices to find the maximum value of the function: 
(0,0)
(0,20)
(24,0)
(18,8)
.
.
I'll do one, you do the rest.
(0,0):
{{{Z=40(0)+35(0)=0}}}