用简便方法计算.5/42/(5/8+5/6)
问题描述：
用简便方法计算.5/42/(5/8+5/6)
答
5/42/(5/8+5/6)
=1/42/(1/8+1/6)
=1/21/(1/4+1/3)
=1/21/(7/12)
=1/21*12/7
=4/49