Question

The perimeter of a rectangle is 80x. The base is two times the height. In terms of x, what are the dimensions of the rectangle?

Answer 1

By definition we have that the perimeter of a rectangle is given by:
 P = 2b + 2h
 Where,
 b: base
 h: height
 Also, as a data of the problem we have:
 base is two times the height:
 b = 2h
 Substituting we have:
 P = 2 (2h) + 2h
 Clearing h:
 6h = P
 h = P / 6
 h = (80x) / 6
 h = (40/3) x
 The base will be
 b = 2h
 b = (80/3) x
 Answer:
 the dimensions of the rectangle are
 b = (80/3) x
 h = (40/3) x
 b. h = 13.3x; b = 26.6x

Answer 2

Answer:
h = 13.3x; b = 26.6x

Explanation:
Perimeter of the rectangle = 2(base+height)
80x = 2(base+height)
base + height = 40x ........> I

Now, we are given that the base is 2 times the height, this means that:
base = 2*height ..........> II

Substitute with II in I:
base + height = 40x
2*height + height = 40x
3*height = 40x
height = 13.3x 

Substitute with the height in equation II to get the base as follows:
base = 2*height 
base = 2 * 13.3x = 26.6x

Hope this helps :)