The perimeter formula for a rectangle is 2(length) + 2(width) = perimeter.
Substituting in the expressions for length, width, and perimeter you get the following equation
2(x + 6) + 2(x + 2) = 64
2x + 12 + 2x + 4 = 64 (Used distributive property to simplify)
4x + 16 = 64 (combined like terms)
4x = 48 (subtracted 16 from both sides of the equation)
x = 12 (divided both sides of the equation by 4)
Width is 12 + 2 or 14 ft and the length is 12 + 6 or 18 ft
Dimensions 18 ft by 14 ft