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put this solution on YOUR website!Let t=ten's digit of unknown number, u=unit's digit of unknown number
So our number is in this form
Now if the digits are reversed then our number becomes
Since the new number is 9 more than the original number, this means
Also, because the sum of the digits of the original number is 11, we know that
And solving for t, we get

Start with the third equation

Plug in

and

Plug in

. Notice how we now have one equation with one unknown

Distribute

Combine like terms on the left side

Combine like terms on the right side

Subtract 11 from both sides

Add 9u to both sides

Combine like terms on the left side

Combine like terms on the right side

Divide both sides by 18 to isolate u

Divide
So we know that the unit's digit is 6

Plug in

Subtract
So the ten's digit is 5
So the original number is 56 and the reversed number is 65