Answer:
Explanation:
Formula
The formula for perimeter is
P = 2L + 2w
Givens
Let the width = w
Length = 3w + 4
P = 80 cm
Solution
P = 2L + 2w
80 = 2(3w + 4) + 2w Remove the brackets
80 = 6w + 8 + 2w Combine
80 = 8w + 8 Subtract 8 from both sides
80-8 = 8w + 8-8 Combine
72 = 8w Divide both sides by 8
72/8 = 8w'8
9 = w
Answer
w = 9
L = 3*w + 4
L = 3*9 + 4
L = 31