7/10 + 9/10 + …. = 27/10


17/9 + ….. - 4/9 = 23/9


5/8 - …. + 13/8 = 15/8


2 5/9 +.....= 3 7/9


4 8/13 - ….. = 1 3/13


1 2/7 + …… = 40/7