Question

Write an equation for the problem and then solve.

Answer 1

Answer:

• first rectangle: 18 by 9
• second rectangle 21 by 6
• x = 9

Step-by-step explanation:

The perimeter in each case is double the sum of the side dimensions. Since the perimeters are equal, the sum of side dimensions will be equal:

  2x +x = (x +12) +(x -3)

  3x = 2x +9 . . . . . . . . collect terms

  x = 9 . . . . . . . . . . . . . subtract 2x

Given this value of x, the dimensions of the first rectangle are ...

  {2x, x} = {2·9, 9} = {18, 9}

And the dimensions of the second rectangle are ...

  {x+12, x-3} = {9+12, 9-3} = {21, 6}