Question

Given the perimeter of a rectangle and either the length or​ width, find the unknown measurement using the appropriate formula.

Answer 1

The width is 18.

step by step:
1. 2 lengths are 20 which is 20+20 that's 40.
2. 76-40= 36
3. Two widths are 36 cm.
4. so do 36÷2 and that equals 18

Answer 2

The formula of a perimeter of a rectangle:

P = 2(w + l)

We have P = 76 cm and l = 20 cm.

Substitute:

2(w + 20) = 76       use distributive property

(2)(w) + (2)(20) = 76

2w + 40 = 76     subtract 40 from both sides

2w = 36       divide both sies by 2

w = 18

Answer: the width = 18 cm