The expression -50 + 100 represents the balance, in dollars, of the banks account after x months. What is the rate of change, in dollars per month, of the bank account balance?

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.