6.25:(x+30)=8分之1
6.25x8=x+30
x+30=50
x=50-30
x=20
3:4=(7﹣x):x
4(7-x)=3x
28-4x=3x
4x+3x=28
7x=28
x=4
x:3又5分之1=16分之5
x:16/5=5/16
x=16/5x5/16
x=1