7/30-2/15-1/6=7/30-4/30-5/30=-2/30=-1/15
5//12+2/5-3/4=25/60+24/60-45/60=4/60=1/15
-4/9+3/10-1/2=-40/90+27/90-45/90=-58/90=-29/45
3/10-5/18-2/15=27/90-25/90-12/90=-10/90=-1/9
-25/42+33/56-1/2=-25/42-21/42+33/56=-23/21+33/56=-184/168+99/168=-85/168
21/22-31/33-1/11=63/66-62/66-6/66=-5/66
-7/12+2/21+1/8=-14/24+4/24+3/24=-7/24
-5/8+1/10+7/25=-125/200+20/200+56/200=-49/200