Below, you will find the mathematical proof that 10 equals 9.99999…. But is that possible or there is something wrong about it? Can you find the error?

x = 9.999999...

10x = 99.999999...

10x - x = 90

9x = 90

x = 10

No error is present in this proof and 10 is actually equal to 9.99999…. The proof is absolutely correct.