能用简算就简算 7/9/11/5+2/9*5/11
问题描述：
能用简算就简算 7/9/11/5+2/9*5/11
答
7/9/11/5+2/9*5/11
=7/9*5/11+2/9*5/11
=(7/9+2/9)*5/11
=5/11