When you simplify, you use the signs in front of the like terms to find if you subtract or not.
4x <u>+ 8y</u> -3x <u>+2y</u>
As you can see, the 4x is positive b/c there's not a sign in front and then the 3x is -3x b/c there is a subtraction in front of it.
With the (y) values, it is addition in front of the 8 so it is 8y. There is an addition side in front of the 2y as well so it is also positive so you add.