6/7*(5/6-1/2)+1/2 简便运算咋算呀?急需
问题描述：
6/7*(5/6-1/2)+1/2 简便运算咋算呀?急需
答
=6/7*5/6-6/7*1/2+1/2
=5/7+1/2*(1-6/7)
=5/7+1/2*6/7
=5/7+3/7
=8/7