To combine like terms, check if there are any terms just like the first one, and we see 6xy. 9xy + 6xy = 15xy. So that is one term. Now I would see if the second term has any terms like the first one, and we see -3y. So -3y + (-3y), we would get -6y. That means our polynomial is now 15xy - 6y, and because this has two terms, it is a binomial. Hope this helps. Please rate, leave a thanks, and mark a brainliest answer. (Not necessarily mine). Thanks, it really helps!
