-1/4+3/5=-5/20+12/20=7/20
-3 8/9+(-2 1/12)= -35/9-25/12= -420/108-225/108= -645/108= -215/36= -5 35/36
-8 9/14+ З 3/7= -112/14+24/7= -112/14+48/14= -64/14= -32/7= -4 4/7
-5 12/35+10= -187/35+350/35= 163/35= 4 23/35
3 6/7+(-6 4/9)=27/7-58/9=243/63-406/63= -163/63= -2 37/63