A group of 4 adults and 5 children is visiting an amusement park. Admission is $15 per adult and $9

A group of 4 adults and 5 children is visiting an amusement park. Admission is $15 per adult and $9 per child. Find the total cost of admission for the group.

Set up the cost function for adults and children:
C(a, c) = 15a + 9c

We want the cost for 4 adults and 5 children
C(4, 5) = 15(4) + 9(5)
C(4, 5) = 60 + 45
C(4, 5) = 105