=(1又2/3一1/3X2.4-1/6×2.4+5/12X2.4)x5=(1又2/3-4/5-2/5+1)x5=4/3
[1又2/3-(1/3-1/6+5/12)*2.4]*5 =[1+2/3-(4-2+5)/12*2.4]*5 =[1+2/3-(7/12)*12/5]*5 =(1+2/3-7/5)*5 =[1+2/3-1-2/5]*5 =10/3-2=4/3
