计算各题 怎样简便就怎样算 解方程

1/3÷11/20÷5/9
=(1/3)x(20/11)x(9/5)
=(1/3)x(9/5)x(20/11)
=(3/5)x(20/11)
=60/55
｛（3/4－1/2）×4/5｝×50％
={(3/4-2/4)x4/5}x50%
=(1/4)x(4/5)x(1/2)
=(1/5)x(1/2)
=1/10
（5/8＋75％）×24
=(5/8+3/4)x24
=(5/8+6/8)x24
=(11/8)x24
=33
（1＋25％）×50
=(1+1/4)x50
=(5/4)x50
=62.5
解方程 x－30％＝7
x-0.3=7
x=7.3
36％x－4.18＝3.02
0.36x=3.02+4.18
0.36x=7.2
x=20
其他的重复或有问题,

1/3÷11/20÷5/9
=(1/3)x(20/11)x(9/5)
=(1/3)x(9/5)x(20/11)
=(3/5)x(20/11)
=60/55
｛（3/4－1/2）×4/5｝×50％
={(3/4-2/4)x4/5}x50%
=(1/4)x(4/5)x(1/2)
=(1/5)x(1/2)
=1/10
...