1除以[(1.1—0.7)乘以0.2]简便运算1除以[(1.1—0.7)乘以0.2]=1÷（0.4*0.2）=1÷0.08=12.5
1÷【（1.1-0.7）X0.2】个人认为先算1.1-0.7=0.4然后将0.2和0.4分数化，1÷【2/5X1/5】,结果12.5
