Hello there!
First, let's categorize our monomials with the proper variables.
3x + 12x
11y - 5y
-10z -4z
Now, we can make these into simpler terms by adding/subtracting the sectioned variables.
3x + 12x = 15x
11y - 5y = 6y
-10z - 4z = -14z
Now let's place our results into an expression as a final answer.
15x + 6y - 14z is your final expression.
I hope this helps!