Answer
$-4y-2z=43$
Work Step by Step
We have $$-9x-8y-z=31$$ $$9x+4y-z=12$$
Adding the equations $$-4y-2z=43$$
You can help us out by revising, improving and updating this answer.
Update this answerAfter you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.