17.31
先做出0.22-0.2065 = 0.0135
然后（3.6*0.015）分之0.00325 ,先找出3.6*0.015 = 0.054
再来0.054 分之0.00325 = 0.06
所以成了：0.0135除以0.06除以0.013 = 17.31