Sam is a waiter at a local restaurant where he earns wages of $5 per hour. sam figures that he also earns about $3 in tips for each person he serves. sam works 6 hours on a particular day. if n represents the number of people sam serves that day, which of the following functions could sam use to figure e, his total earnings for the day?

a. e(n) = 3n
b. e(n) = 3n + 30
c. e(n) = 5n + 18