A student collecting money for a charity is donating $12 of his own money. He asks friends to give $5 each. Write a rule in function notation to find how much he will donate in all. Let p represent then number of friends who give money.
a. f(p) = 12p + 5
b. f(p) = 12 + 5p
c. f(p) = 12 + 5 + p
d. (p) = 17p