To answer let the length of the rectangle be represented by L. With the condition from the problem, the width is L - 6. The perimeter of the rectangle is twice the sum of the length and width. With the given values, the equation becomes,
P = 2L + 2W
68 in = 2L + 2(L - 6)
The value of L from the equation is 20 inches. Therefore, the width is equal to 14 inches.