• # question_answer The sum of the digits of a two-digit number is 12. The number obtained by interchanging the two digits exceeds the given number by 18. Find the number.                A)  57                  B)  75                  C)  85      D)  58

Let the unit's and ten's digits in the number be y and x respectively. So, the number be$10x+y$. According to the question, $x+y=12$                             ?..(1) Also, $10x+y+18=10y+x$ $\Rightarrow$ $9x-9y=-18$$\Rightarrow$$x-y=-2~$    .....(2) Solving (1) and (2), we get $x=5$and $y=7$ $\therefore$   Required number is 57.