A rectangle has a width 5 feet shorter than it’s length. The perimeter is 90 feet. What is the width?

Question

Need help pleas I don’t know how to do this i need the answer please. 

Answer 1

First:  the word "it's" always means "it is".  You need to use "its" for other meanings, such as this one.

A rectangle has a width 5 feet shorter than it’s length

w = l - 5

perimeter is 90 fee

P = 90 = 2l + 2w

Substitute:

90 = 2l + 2(l - 5)

90 = 2l + 2l - 10

100 = 4l

l = 25

w = 20

Answer 2

If W represents the width, then the length is W+5. The perimeter of a rectangle is 2W + 2L, so in this case:

90 = 2W + 2(W+5) = 2W + 2W + 10 = 4W + 10

Solve for W