4*(7/20+1/12)-2/5简便计算

问题描述:

4*(7/20+1/12)-2/5简便计算

4*(7/20+1/12)- 2/5
=(7/(20/4)+1/(12/4))- 2/5
=7/5+1/3 - 2/5
=(7/5 - 2/5)+1/3
=1+1/3
=4/3