I'm sorry to say, but that does not seem correct.

If there are three sections then we have a total of 4 x's.

So:Code:_______________________________________________ | | | | | | | | | | | | x | | | | || || y

P = 100 = 4x + 2y --> y = 100/2 - 4x/2 = 50 - 2x

A = x*y = x(50 - 2x) = 50x - 2x^2

A' = 50 - 4x

A' = 0 = 50 - 4x --> x = 50/4 = 12.5

P = 100 = 4(12.5) + 2y --> y = (100 - 50)/2 = 25

A = (12.5)(25) = 312.5