(3 又7/11+1又 12/13)+(1又 5/11+10/13)=(3又 7/11+1又5/11)+(1 又12/13+10/13)=5又1/11+2又9/13=7又112/143
3 又7/11+1又 12/13)+(1又 5/11+10/13)=(3又 7/11+1又5/11)+(1 又12/13+10/13)=5又1/11+2又9/13=7又112/143