Question

The sum of the digits of a two-digit number is 7 and if 9 is added to the number, the digits are reversed. Find the number.

Answer 1

First digit is 0 and second is 7

Answer 2

Let first digit be x and second digit be y .

Let original no be = 10 x X + Y

A/Q

1. X + Y = 7

X= 7-Y

2. 10 x X + Y + 9 = 10 x Y + X

10X + Y + 9 = 10Y + X

10X - X + 9 = 10Y - Y

9X + 9 = 9Y

9X - 9Y = -9

X - Y = -1

7-Y-Y = -1

-2Y = -1- -7

-2Y = -8

Y = 4

X = 7-4

= 3

Original no = 34