40%x+30=80
0.4x=50
x=125
x/4分之3=40
12/x=40
x=0.3
y—60%y=20
y-60%y=20
40%y=20
y=20÷40%
y=50
8分之3+8分之3m=8分之5
3+3m/8=5/8
(3+3m)×8=40
m=2/3