5/12+3/8+7/12+5/8=(5/12+7/12)+(3/8+5/8)=221/29-5/8+8/29=(21/29+8/29)-5/8=3/83/17+5/13-3/17+4/13=(3/17-3/17)+(5/13+4/13)=9/13
(5/12+7/12)+(3/8+5/8)=2(21/29+29/8)-5/8=1-5/8=3/8(3/17-3/17)+(5/13+4/13)=0+9/13=9/13