求助数学题

图示一个小正方形在一个大正方形中间。大小的区别就是过道。。。帮忙  

The figure shows a square patio surrounded by a walkway of width x meters.  If the area of the walkway is 132 square meters and the width of the patio is 5 meters greater than the width of the walkway, what is the area of the patio, in square meters?

A.      56

B.      64

C.      68

D.      81

E.      100

是太简单吗？ 没人帮忙。。。

大正方形的面积是（3x+5）^2=132+(x+5)^2.可以推出x=3.

则patio的边长=8，面积是64.