Stewart has a home-based business putting on children's parties. He charges $60 to design the party and then $6.00 per child. Write a function rule that relates the total cost of the party to the number of children n.

60 is constant

6 per child is variable

Let c = number of children

total cost = 60 + 6c

If there are n children, and each additional child who joins will add another $6 to the cost, then the cost due to the number of children will be 6n. We also have the fixed cost of $60, no matter how many children join. Therefore, we add up these costs to get Cost = f (n) = 60 + 6n.