7\8 - (-3\10)=
11\12 - 17\18 =
-3\7- 9\14=

7\8 - (-3\10)= 7/8 + 3/10 = 35/40 + 12/40 = 47/40 = 1 7/4011\12 - 17\18 = 11/12 - 17/18 = 33/36 - 34/36 = - 1/36-3\7- 9\14= - 6/14 - 9/14 = - 15/14 = - 1 1/14