Original number = 10x + y - such considered as it is a two digit number.
The sum of digits is:
⇒ x + y = 8
⇒ y = 8 -x ← Equation 1
The interchange number: 10y + x
If they interchange, the number is 36 less than original number.
⇒ 10y + x = (10x + y) - 36 (add/subtract integers)
⇒ 10y - y = 10x - x - 36 (simplify)
⇒ 9y = 9x - 36 (divide both sides by 9)
⇒ y = x - 4 ← Equation 2
Substitute Both the equations:
⇒ x - 4 = 8 - x ⇒ 2x = 12 ⇒ x = 6
Then find y : x - 4 = 6 - 4 = 2
- Original Number: 10x + y = 10(6) + 2 = 62
- The Interchange number: 10y + x = 10(2) + 6 = 26
Original Number is 62