1、(3/10+1/4)÷2/5
=(6/20+5/20)×5/2
=11/20×5/2
=11/8
2、2/3×(1-1/8-5/8)
=2/3×2/8
=2/3x1/4
=1/6
3、45×(1+1/5)
=45×1+45×1/5
=45+9
=54
4、[1-(1/3+1/2]÷2/9
=(1-5/6)×9/2
=1/6×9/2
=3/4
5、(5/6+3/8)÷(5/6-3/8)
=(20/24+9/24)÷(20/24-9/24)
=29/24 ÷ 11/24
=29/11