Question 629508
Let x = units digit
    y = ten's digit
The value of the number is x + 10y
The new value after reversing the digits is 10x + y

Equations:
x + y = 10 and
10x + y = x + 10y - 36 or 9x - 9y = -36  or  x - y = -4
Add the 2 equations, the result is 2x = 6
so x = 3 and y = 7
The original number is {{{highlight(73)}}}