Hi lakeheadca;

We have the 2 equations:

P = 100 = 2L + 2W

A = 25 = L * W These are easy. But not easy to solve for all those variables. So we try to eliminate one. We solve for the L from the first equation.

L = 100 - 2W = 50 - W

25 = L * W Substitute 50 - W for L

25 = ( 50 - W ) W This is a quadratic, so expand it.

25 = 50W - W^2

W^2 - 50 W + 25 = 0

Now solve by the quadratic formula. Are you Okay with this? Or do you need more help? After you get the answer I will go over the equations with you.