Explanation:
A.
C(250) means
c = 10n + 45 with n = 250
so,
10×250 + 45 = 2500 + 45 = 2545
the costs for a sports banquet with 250 attending people is 2545.
it means that every participant causes costs of 10, and then there are fixed costs of 45 that will always happen, even if there are 0 guests.
B.
C(n) = 4295 = 10n + 45
4250 = 10n
n = 425
when the costs are 4295, then there are 425 guests attending.