1 1/3 + 2/3= 4/3+2/3=6/3=2
2 3/5+ 3 4/15=13/5+ 49/15=39/15+49/15=88/15=5 13/15
9 1/9 + 1 8/9=10/9+17/9=27/9=3
1 12/18 - 12/18= 30/18 -12/18=18/18=1
5 11/15 - 5 8/15=86/15-83/15=3/15=1/5
1 13/15 - 17/20 =28/15-17/20=112/60-51/60=61/60=1 1/60
3 1/8 - 2 - 4/5=25/8-2-4/5=125/40-80/40-32/40=13/40
4 - (2 3/4 + 1/5)=4-(11/4+1/5)=4-(55/20+4/20)=4-59/20=80/20-59/20=21/20=1 1/20