A) 2L + 2W = 48
B) L * W = 140
B) W = 140 / L
Inputting this to equation A)
A) 2L + 2*(140 /L) = 48
L + 140/L = 24
Multiplying both sides by "L"
L² + 140 = 24L
L² -24L +140 = 0
(L -10) * (L-14) = 0
L= 10
L = 14
If length = 10 then width =14
If length = 14 then width = 10