`x xx 9 - 9 = 0,9`
`=> x xx 9 = 0,9 + 9`
`=> x xx 9 = 9,9`
`=> x = 9,9 : 9`
`=> x = 1,1`
\(xX9-9=0,9\)
\(xX9\) \(=0,9+9\)
\(xX9\) \(=9,9\)
\(x\) \(=9,9:9\)
\(x\) \(=1,1\)
\(x\times9-9=0,9\\ \rightarrow x\times9=0,9+9\\ \rightarrow x\times9=9,9\\ \rightarrow x=9,9:1\\ \rightarrow x=1,1\)