Question 349945
Let x = the 10s digit, Let y = the units
then
10x + y = "the original number"
10y + x = the "new number"
:
Just write an equation for what it says:
:
The sum of the digits in a two-digit number is 8.
x + y = 8
:
When the digits are reversed, the new number is 18 less than the original number.
10y + x = 10x + y - 18
you can simplify, combine like terms
10y - y = 10x - x - 18
9y = 9x - 18
Divide by 9
y = x - 2