A=5/81 * 81/7=(5*81)/(81*7)=5/7
B= 9/70 * 7/90=(9*7)/(70*90)=(9*7)/(7*10*9*10)=1/100
C=9/70 * 50/27=(9*70)/(50*27)=(9*50)/(70*27)=(9*5*10)/(7*10*9*3)=5/21
D=9/20 *16/15=(9*20)/(16*15)=(3*3*5*4)/(4*4*5*3)=3/4
A=8-1/6=48/6-1/6=47/6
B=8/3-3/15=40/15-3/15=37/15
C=1/10+8/10=9/10
D=9/7-1=9/7-7/7=2/7
E=9/30-3/6=3/10-1/2=3/10-5/10=-2/10=-1/5
F=6-5/3=18/3-5/3=13/3
G=10/6-1=5/3-1=5/3-3/3=2/3
H=9/4+3/2=9/4+6/4=15/4