4x+2x^2+3x-2x+7
First, you would combine like terms. In this case, you would add 4x and 3x then subtract 2x.
2x^2+5x+7
5x^2-2x+3+4x-2x^2
Once again, you must combine like terms. Subtract 2x^2 from 5x^2, then subtract 2x from 4x.
3x^2+2x+3
There you go! Hope it helps
-Lacy