A- 1/5+3/5=4/5
B- 9/7-3/7=6/7
C- 1/3+1/6=2/6+1/6=3/6=1/2
D- 4/5-3/10=8/10-3/10=5/10=1/2
E- 2+1/3=2*3/1*3+1/3=6/3+1/3=7/3
F- 2/5+1/10-3/20=2*2/5*2+1/10-3/20=4/10+1/10-3/20=5/10-3/20=5*2/10*2-3/20=10/20-3/20=7/20