14分之9/（6分之5-4分之3）*24分之7 =9/14/(10/12-9/12)*7/24=9/14*12*7/24=63/16816分之5*7分之4+1/5分之16+7分之3*16分之5 =5/16*4/7+1*5/16+3/7*5/16=5/16*(4/7+1+3/7)=5/16*2=5/835.5+（2.8-0.8）/80%=35.5+2/0....