=-(6/10+13/15):22/15+34/23(1/2+6/11)=-(3/5+13/15):22/15+34/23(11/22+12/22)=-(9/15+13/15):22/15+34/23(11/22+12/22)=-(22/15):22/15+24/23(23/22)=-1+17/11=-1+1 6/11= 6/11