The equation 9+12m=6+15(m-1) models the following situation: Movie-rental company A charges a sign up fee of $9 plus $12 per month, and company B charges $6 for the first month plus $15 per month after that. At a certain number of months, the cost of the two companies is equal.
Which equation is a simplified version of the one above?
X 3m = 15
9 + 15m = 12m - 1
3m = 18
9 + 6 - 15 = 15m - 12m

At___ months, the prices are the same.وا