Explain and give me the answer please

Factor the expression using gcf 9b+45

Ijust need these 2 questions answered (the second pic is just confirmation i'm not confident in that answer)

Asales representative from a local radio station is trying to convince the owner of a small fitness club to advertise on her station. the representative says that if the owner begins advertising on the station today, the club's total number of members will grow exponentially each month. she uses the given expression to model the number of club members, in hundreds, after advertising for t months.