A=5/6-1/3=5/6-2/6=3/6=1/2
B=7/9-1/(-27)=7/9+1/27=21/27+1/27=22/27
C=-8/5+23/50=-80/50+23/50=-57/50
D=45/15-7/3=9/3-7/2=2/3
E=4/11+2=4/11+22/11=26/11
F=8/(-91)-1/7=-8/91-1/7=-56/637-91/637=-147/637
G=5/2--45/4+2/8=5/2+45/4+2/8=10/4+45/4+1/4=56/4=18
H=4-5/(-49)+(-8/7)=4+5/49-8/7=196/49+5/49-56/49=145/49