看起来这题很简单，搜过都没有人问的，但我就是算来算去就是算不出来，麻烦各位指点。

GWD18-Q24:

The positive numbers w, x, y, and z are such that x is 20 percent greater than y, y is 20 percent greater than z, and w is 20 percent less than x. What percent greater than z is w ?

A. 15.2%

B. 16.0%

C. 20.0%

D. 23.2%

E. 24.8%

x=1.2y,y=1.2z,w=80%x

then 1.2*1.2z=w/0.8

w=1.152z

(w-z)/z=15.2%