simply the expression -4+2x+8 ??

2x+4

2x + 4

or
2(x+2)

but what happens to the 8?

8 - 4 = 4

ohh okay...so if i said 4x+1+(-3) it would be like 4x+1-3 then i would do:

3-1=2
so it would be 4x+2 ?

When you simplify, you combine like terms.

In your expression you have one unknown >> 2x.

You have two known numbers >> + 8 and - 4.

Please study Cindy's and Damon's answers. They both posted the correct answer.

To simplify the expression -4 + 2x + 8, we can combine like terms. Like terms have the same variable (in this case, x) raised to the same power.

First, we can combine -4 and 8, since they are constants without any x term:
-4 + 8 = 4

So now the expression becomes 4 + 2x.

Now there are no more like terms to combine, so the expression -4 + 2x + 8 is simplified to 4 + 2x.