2-7/8=?
4 5/7+2 1/7=?
4 5/7-2 1/7=?
2 1/6+1 5/6=?
2 1/6-1 5/6=?

1) 2 + 7/8 = 18/8 + 7/8 = 25/8 = 3 1/8 
2) 2 - 7/8 = 16/8 - 7/8 = 9/8 = 1 1/8
3) 4 5/7 + 2 1/7 = 33/7 + 15/7 = 48/7 = 6 6/7
4) 4 5/7 - 2 1/7 = 33/7 - 15/7 = 18/7 = 2 4/7
5) 2 1/6 + 1 5/6 = 3 6/6 = 4
6) 2 1/6 - 1 5/6 = 13/6 - 11/6 = 2/6 = 1/3