Man wants to fence around a rectangular garden, length is twice as long as width, what are the garden's dimensions if the perimeter is 60?

P = 2W + 2L

...length is twice as long as width,

therefore

L = 2W

Substitute

P = 2W + 2(2W)

P = 2W + 4W

P = 6W

60 = 6W

W = 10

L =  2W

L = 20

ANS L = 20, W = 10

_______________________

Or use ratios

L:W = 2:1

2 + 1 = 3 parts

W = 1 part = 60/3 = 20

L = 2 parts = 40

There are 4 sides with 2 L's and 2 W's, so divide each by 2

W = 20/2 = 10

L = 40/2 = 20

You are 18. Why are your simple algebra abilities so poor ?? No math skills, no high paying job. 

Man wants to fence around a rectangular garden, length is twice as long as width, what are the garden's dimensions if the perimeter is 60?

l + w = 30

l = 2w

width = 10

length = 20

Length = 20

Width = 10

One dimension is X.  the other is 2X

X + X + 2X + 2X = 60

Solve for X

10x20. I think.