1) 3 4/9+(-4 1/3)= (27+4)/9-(12+1)/3=31/9-13/3= (31- 13×3)/9=(31-39)/9= -8/9
2) 3 7/8+ (-2 1/9)= (24+7)/8- (18+1)/9=(31×9-19×8)/72=(279-152)/72=127/72=1 55/72
3) 3 7/9+ (-2 4/15)=(27+7)/9-(30+4)/15=34/9-34/15=1/3 (34/3-34/5)= 1/3 (34×5-34×3)/15=1/3×68/15=68/45= 1 23/45
4) -8/11+ 1 5/7= (-8×7)/11+(12×11)/7=(-56+132)/77=76/77