Question

The sum of a 2 digit number and the number obtained by reversing the digit is 77 if the digits of the number differ by 3 find the number

Answer 1

Let us assume x and y are the two digits of a number.
Therefore, The two digit number = 10x + y and the reverse number is 10y + x
Given: 
10x + y + 10y + x = 77
11x + 11y = 77
x + y = 7 -------------1
y = 7 - x
Also given:
x - y = 3  ---------------2
By adding equation 1 and equation 2
2x = 10
x = 5
Therefore, y = 7 - x = 7- 5 = 2
The two digit number = 10x + y = (10 * 5) + 2 = 52