Question

The length of a rectangle is twice its width.

Answer 1

P = 2l + 2w
l = 2w

48 = 2(2w) + 2w
48 = 4w + 2w
48 = 6w
8 = w

l = 2w
l = 2(8)
l = 16

48 = 2(16) + 2(8)
48 = 32 + 16
48 = 48

Answer:
length = 16
width = 8

Answer 2

L = 2w
perimeter  = 2l + 2w
P = 48
Plug in all the given
48 = 2(2w) + 2w
combine like terms
48 = 4w + 2w
48 = 6w
divide both sides by 6
8 = w
The width is 8

l = 2w
l = 2(8)
l = 16
The length is 16

Hope this helps