72 is dividable by 3. It is divisible by 3 because when you add 7 and 2, you get 9. According to the tests for divisibility, if the sum of the digits is divisible by 3, then the whole number is. 9 is divisible by 3, therefore 72 is as well.
(1,-4) is the answer reason why is you add the equations in order to solve for the first variable plug it in the equations in order to solve for the remaining variables
