(x-90)/9=(x+39*10)/39
(x-90)/9=(x+390)/39
x/9-10=x/39+10
x/9=x/39+10+10
x/9-x/39=20
39/351x-9/351x=20
30/351x=20
x=20*351/30
x=234
很高兴为你解答,