The ten's digit of a 2-digit number is greater than the units digit by 7. If we subtract 63 from the number, the new number obtained is a number formed by interchange of the digits. Find the number.

Let the unit's digit of the number be $$y$$ and ten's digit be $$x$$

=> Number = $$10x + y$$

According to ques, =>$$x - y = 7$$ --------------(i)

According to question, => $$10x + y - 63 = 10y + x$$

=> $$9x - 9y = 63$$

=> $$x - y = \frac{63}{9} = 7$$ --------------(ii)

Equations (i) and (ii) are same and thus we have two variables and one equation

Number can be = 92 , 81 and thus the solution cannot be determined.

=> Ans - (D)