Question

The length of a rectangle is 3 time the width. the perimeter is 65.6 cm. find the width.

Answer 1

The width is 8.2
Perimeter = 2W + 2L (there are four sides of a rectangle, two longer sides, two shorter, W and L) 

65.6 = 2W + 2L 
L = 3W so substitute 3W in for L 
65.6 = 2W +2 (3W) 
65.6 = 8W 
W = 8.2 cm 
L = 3(8.2) 
L = 24.6cm 

Answer 2

I misread the question.
3w=l
2l+2w=65.6
8w=65.6
w=8.2
l=24.6