二分之一除以八分之五加四分之一乘五分之三
=1/2÷5/8+1/4x3/5
=1/2x8/5+1/4x3/5
=1/2(1+3/5)+1/4x3/5
=1/2+1/2x3/5+1/4x3/5
=1/2+(1/2+1/4)3/5
=1/2+3/4x3/5
=1/2+9/20
=10/20+9/20
=19/20
二分之一除以八分之五
就是1/2*8/5=2/4*8/5
2/4*8/5+1/4*3/5=19/20
=(1/2+1/4)X3/5+1/2
=19/20
1/2÷5/8+1/4*3/5
=1/2*16/10+1/2*3/10
=1/2*19/10
=19/20