12/7-(1/3*15/7+4/5)=?简便运算

问题描述:

12/7-(1/3*15/7+4/5)=?简便运算

12/7-(1/3*15/7+4/5)
=12/7-(5/7+4/5)
=12/7-5/7-4/5
=1-4/5
=1/5