Does someone know the answer for this?

If i have 20$ and i gave 5$ away how much i got

What is the effect on the graph of the function f(x)=x when f(x) is replaced with -f(x)+4

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.