So, there are 3 different variables. The parenthesis does not matter in this case except for distributing the negative sign. 5x+y+3z-x-3y-9z. So, lets start with x first. 5x-x is 4x. Keep that in mind or write it down. Then, y. y-3y is -2y. Finally z, 3z-9z is -6z. 4x-2y-9z is your final answer.
