The sum of the digits of a two-digit number is 10. If we interchange the digits, then the new number formed is 54 less than the original number. What is the original number? (Hint: 23= 2(10)+3)
x is tens and y is units
x + y = 10
(x + 10y) + 54 = (10x + y)
10y + x + 54 = 10x + y
9x - 9y = 54
x - y = 6
Then we will find the average of 10 and 6 to find x and y.
x = (10+6)/2 = 8
8 - y = 6
y = 2
