Add alike terms. Basically you add stuff together with the same variable! Since -8y and +3y have a y variable, they can be added together. Same with x.
-8y + 3y = -5y. This is because you’re adding 3 from a negative number.
5x - 9x = -4x. You’re subtracting 9 from a positive number.
That is as simple as it can get, so you put those two numbers in the same equation.
The simplest expression is:
-5y - 4x
