提出一个1/13，然后通分原式=1/13*(5/6+5/2+5/3)=1/13*(5/6+15/6+10/6)=5/13
=5/13×(1/6+1/2+1/3)=5/13×1=5/13
=5/13（1/6+1/2+1/3）=5/13*1=5/13
