Question

Q) The sum of digits of a two digit number is '7' .If the digits are reversed the new number decreased by two equals twice the original number .FIND THE NUMBER ?Board Question 2012

Answer 1

Let us assume, x and y are the two digits of the two-digit number 

Therefore, the two-digit number = 10x + y and reversed number = 10y + x

Given:

x + y = 7 ---------------1

also given:

10y + x - 2 = 2 (10x + y)

10y + x - 2 = 20x + 2y

8y - 19x = 2 ---------2

Multiply equation 2 by 8

8x + 8y = 56 ----------------3

subtract equation 2 from the equation 3

27x = 54
x = 2

Therefore, y = 7 - x = 7 - 2 = 5

Therefore, the two-digit number = 10x + y = 10 * 2 + 5 = 25

Answer - The original number = 25