A rectangle is 3 inches long and 2x inches wide. The value of the perimeter (in inches) is equal to the value of the area (in square inches). Find x.

The perimeter of the rectangle is equal to the doubled sum of the sides, and the area is equal to the product of the sides. So we have the following equation

3 x 2x = 2 (3 + 2x)

6x = 6 + 4x

2x = 6

x = 3