25*6.4*12.5 （3-1/4-5/12）÷2/3 3.25*5.8+67.5*0.58 5/7÷（7-6*2/3）

25*6.4*12.5=(25x4x4)x(0.8x12.5)=400x10=4000 （3-1/4-5/12）÷2/3 =3x3/2-1/4x3/2-5/12x3/2=9/2-3/8-5/8=9/2-1=7/23.25*5.8+67.5*0.58 =(3.25+6.75)x5.8=10x5.8=585/7÷（7-6*2/3）=5/7÷（7-4）=5/7÷3=5/21请好...