5x - 12y + 8x + 2x² + 4x²
Combine like terms
You can keep the variables/exponents the same if you are adding or subtracting the same like terms (same variable to the same power)
5x - 12y + 8x + 2x² + 4x²
We can combine 5x + 8x and 2x² + 4x² because they are like terms; -12y will be left alone
13x - 12y + 6x² is your answer