Directions: Simplify the following monomials (if possible).
12.) 12b + 8a - 10b
13.) 13y² + 9y + 4y² - 31y
14.) 10m²n + 7mn² - m²n
15.) Find the sum of 16y² and -5y²
16.) Find the difference of 10x²y and 2x²y

-ANYONE PLEASE HELP ME I REALLY NEED THE ANSWER RIGHT NOW BECAUSE I HAVE TO PASS THIS LATER AND THE DEADLINE IS TODAY I HOPE Y'ALL CAN HELP ME:(
I'LL MARK YOU AS THE BRAINLIEST!​