Would like to know how to solve - 7 (x-4y-9z)

-7x + 28y + 63z

let me know if you dont know how I did this

Take - 7 and multiply it by everything inside the parenthesis and go from there.

-7x+28y+63z

you have to add because the outcomes are positive.

I will let you handle the rest since your in college.

you got this your smart!