In your notations, x is the length (although it would be more logical to make it the width . . . ) 82 = 2(x-6) + 2x <<<---=== Correct ! Next steps should be: 41 = x - 6 + x 41 + 6 = 2x 47 = 2x x = 47/2 = 23.5 <<<---=== it is your LENGTH Then you should find the WIDTH: W = 23.5 - 6 = 17.5.