3/5×0.8+0.6×1/5=3/5×0.8+(0.2×3)×1/5=3/5×0.8+3/5×0.2=3/5×(0.8+0.2)=3/5
观察:3/5=0.63/5×0.8+0.6×1/5=3/5×0.8+3/5×0.2=3/5×(0.8+0.2)=3/5×1=3/5
3/5x0.8+0.6x1/5=3/5X4/5+3/5x1/5=(4/5+1/5)X3/5=3/5
=1/5×0.8×3+0.6×1/5=1/5×(2.4+0.6)=3/5