3/2+5/6-7/12+9/20-11/30简便计算=90/60+50/60一35/60+27/60一22/60=(90/60+50/60+27/60)一(35/60+22/60)=167/60一57/60=110/60=11/6=1又5/6
先通分为90/60+50/60-35/60+27/60-22/60=11/6
3/25328/564#2861@553
傻傻滴
