QUESTION IN DESCRIPTION PLEASE HELP

Question

You are ordering photo prints online to send out to all your friends for the holidays. The first 20 prints cost 12¢ each. If you order more than 20, The price of the additional prints goes down to 8 cents each.
A. Write a function to describe the cost of prints
B. What is the cost if you buy 16 prints?
C. What is the cost if you buy 35 prints?
D. What is the cost if you buy 112 prints?

Answer 1

16 prints cost 12 x 16 = $1.92

35 prints cost 20 x 12 + 15 x 8 = 2.40 + 1.20 = $3.60

112 prints cost 20x 12 + 92 x 8 = 2.40 + 7.36 = $9,76

C = 12p if p is 20 or less

C= 12p - 4(p-20) = 12p-4p + 280 = 80 + 8p

C = 80+8p if p>20

C = 80 +8(112) = 80 + 896 = $9.76

C = 80 + 8(35) = 80 + 280 = $3.60

C = 80 + 8(16) won't work for 16 prints because there's no 4 cent discount as in p>20

C = 12p = 12(16) = $1.92 when p =20 or less