Respuesta :
Answer: 9x
Explanation: Both 5x and 4x have the same variable (x) so they can add to each other. If the problem was 5x + 4y, you wouldn't be able to simplify it any more because the variables (x and y) are different.
Explanation: Both 5x and 4x have the same variable (x) so they can add to each other. If the problem was 5x + 4y, you wouldn't be able to simplify it any more because the variables (x and y) are different.