1 3/7+ 2 7/8 17 1/3- 8 5/9 12 1/4- 3 5/6+5 7/8

1) 1 3/7+2 7/8=1 24/56+2 49/56=3 73/56= 4 17/56 2) 17 1/3-8 5/9=17 6/18-8 10/18=16 24/18-8 10/18=8 14/18=8 7/9 3) 12 1/4-3 5/6+ 5 7/8=12 3/12-3 10/12=9 15/12-3 10/12=8 5/12+5 7/8=8 10/24+5 21/24=13 31/24=14 7/24