1)6 4/5+1 8/15=34/5+23/15=102/15+23/15=125/15=8 5/15=8 1/3
2)3/7+129 4/7=3/7+907/7=910/7=130
3)8 7/12-2 5/6+3 4/9=103/12-17/6+31/9=309/36-102/36+124/36=331/36=9 7/36
4)8 7/12-(2 5/6+3 4/9)=103/12-(17/6+31/9)=309/36-(102/36+124/36)=309/36-226/36=83/36=2 11/36