The 130 juniors at Smithers High School are taking a class trip. Three buses will be taking the
students and chaperones to their destination, and
each bus can hold up to 45 people. The first bus
will be filled to capacity, followed by the second
and third buses. The function f(x) describes the
total number of people on the first bus, where x is
the number of minutes spent loading the bus. If
the first bus is boarded at a rate of 15 people per
minute, what is the domain of the function?