Step-by-step explanation: Since both terms contain an <em>x</em>, you can add them together by simply adding their coefficients. Coefficients are just your number in front of your variables. So if -2 + 9 = +7, -2x + 9x = +7x.
To find the answer just multiply 7 by 3 and that's 21, so just add a negative sign to 21 and you get -21. I hope this helps :) please give me brainliest :)
