1、
[4/5×(3/8-1/4)]÷2/3
=4/5×1/8÷2/3
=1/10×3/2
=1/15
2、
(45×2/9-6)÷50%
=4÷50%
=8
设这个数是x,则
x50%=45×2/9-6
解得x=8