Question 279490
The sum of the digits of a two- digit number is 12. If 36 is added to the number, then the number obtained is the original with its digits interchanged. Find the original number.

Let x be in the tens place and y in units place

x+y =12

10x+y+36 = 10y+x

10x-10y+y-x+36=0

9x-9y=-36
x+y=12

9x+9y=108

18x=72

x=4

x+y=7 but x=4 so y=3  Number 43