Your answer to number 17 is x=4 because you replace y with 0 and you get 4x-3(0)=16. Then you multiply 3 by 0 to get 0 and get 4x=16 as ur equation. Then you can divide both sides by 4 to get 4 as your x.
Your answer to number 19 is 0 because 3(2x)-6x=0 is also known as 6x-6x=0 which equals 0.
