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

4/5+2/3=12/15+10/15=22/15=1 7/155/6+7/9=15/18+14/18=29/18=1 11/183/4-1/6=9/12-2/12=7/127/8-5/6=21/24-20/24=1/24