W*(2W+4) = 30 square yards (the area).
W*(W+2) = 15.
So, 15 is presented as the product of two factors that differ by 2.
Hence, guessing mentally, W = 3; W + 2 = 5.
Or you can solve the equation (1) formally.
ANSWER. W = 3 yards; L = 2W + 4 = 2*3+4 = 10 yards.