math
posted by me on .
if the width of a rectangle is 5 inches shorter than the length and the perimeter of the rectangle is 80 inches.
how do you set up the equation for the perimeter involving only L and how do you solve this in a linear equation algebraically to find the length and the width

let the length be L
"..the width of a rectangle is 5 inches shorter than the length"
so width = L  5
Twice the width + twice the length = 80
2L + 2(L5) = 80
take it from there.
once you have L, evaluate L5 for the width