10又9/20/[(7又5/12-1又4/9)*1.8-0.65/2又1/6]=10又9/20/[(6+5/12-4/9)*9/5-0.65/(13/6)]=10又9/20/[(54/5+3/4-4/5)-3/10]=(10+9/20)/[10+9/20]=1
