0.8*1.2*12.5*5=（0.8*12.5）*(1.2*5)=40*6=60
0.8*1.2*12.5*5=(0.8*5)*(1.2*12.5)=4*(0.3*4*12.5)=4*0.3*50=4*15=60
.8*12.5*(1.2*5)=10.00*6.0=60
4/5*5/4*(12+0.5)*5=1*(60+2.5)=62.5
