mkay so when working with simplifying any expressions like that, you wanna start with getting rid of your brackets. To do that, you simply take the number directly outside the bracket and you multiply it by everything inside. Let's take -9(m+2) first. You have to multiply everything inside the bracket by -9, so you have -9*m and -9*2, so you end up with -9m and -18. Now you do that to the second part of the equation (4*6 and 4*-7m) and you end up with 24 and -28m. Now you join all your terms together, and you have -9m-18+24-28m. Now all you do is add like terms (so -9m + -28m and -18+24) and you end up with a simplified expression of -37m+6. I hope this helped a little :)).
For this case we have that by definition, a monomial is an algebraic expression that consists of a single term or in which the terms that form it are related by the product operation.
