To make things easier, we can assume a value of x in order to substitute to each expression and obtain the side length of each. We can calculate for perimeter of each square. Then, compare them. We do as follows:
Assume x = 4
Square A
2x - 7 = 2(4) - 7 = 1
P = 4(1) = 4
Square B
-4x + 18 = -4(4) + 18 = 2
P = 4(2) = 8
Therefore, the perimeter of B is 2 than the perimeter of A.
