Area is length * width, so lw = 15
l = 2+w
so w(2+w) = 15 or w^2 +2w -15 = 0
Use quadratic formula to get (-2 +/- sqrt(4-4*1*-15))/2 or -5 and 3, but width cannot be negative, so 3 is the width. Plug into length, 3+2 = 5. Length is 5.
2*5 + 2*3 = 10+6 or 16 ft.
