3.6*25.4+37.9*6.4=3343.6×25.4+37.9×6.4 =3.6×25.4+(25.4+12.5)×6.4 =3.6×25.4+25.4×6.4+12.5×6.4 =3.6×25.4+25.4×6.4+12.5×8×0.8 =25.4×(3.6+6.4)+100×0.8 =254+80 =334
