Juan lives in a state where sales tax is 6%. This means you can find the total cost of an item, including tax, by using the expression c + 0.06c, where c is the pre-tax price of the item. Use the expression to find the total cost of an item that has a pre-tax price of $72.00.

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.