Question: Susie is designing a stand for an exhibition. It is to have display screens round three sides and to be open on the other side. 40 m of screens are available for the stand and the owners want a rectangular floor space of at least 150 square metres.

What limits must Susie work within for the lengths of the sides of the stand?

total length of screen = 40 + 40 + 40 = 120

perimeter = 2l + w

2l +w = 120

w = 120 -2l

or

i need up with this but

can some one tell me what i am doing wrong

thank you for helping me