3/10乘3/8+3/8+7/10乘0.375
=3/10X3/8+3/8+7/10X3/8
=3/8X(3/10+1+7/10)
=3/8X2=3/4=0.75
3/4乘5/8+0.75乘37.5%
=3/4X5/8+3/4X3/8
=3/4X(5/8+3/8)
=3/4X1=3/4=0.75