3+8 5/12=(8+3) + 5/12 = 11 5/12

10 6/7 -3=(10-3) + 6/7=7 6/7

4 2/13+ 5 7/13= (4+5)  + (2/13 + 7/13) = 9 9/13

8+ 7/12- 4 2/12 = (8-4) + (7/12-2/12) = 4 5/12

4 8/11+5 7/11=(4 + 5) + (8/11 + 7/11) = 9 15/11= 10 4/11

7 5/9- 2 8/9=(7-1) + (5/9 +9) - 2 8/9=6 14/9 - 2 8/9 = (6-2)+(14/9 - 8/9) = 4 6/9

7-3/8= (7-1) + 8/8 - 3/8 = 6 8/8 - 3/8 = 6 5/8

10 - 3 7/15= (10-1) + 15/15 - 3 7/15= 9 15/15 - 3 7/15= (9-3)+ (15/15 - 7/15) = 6 8/15