Precalculus question worth 20 points

i don't get this question, if anyone could that'd be great!

santa's wonderland is an extravagant holiday light display that is open from early november through january each year. the entry fee is $15 per vehicle for up to and including 5 people, with an additional $1.50 for each person over 5. express this information as a piecewise function of x, where x represents the number of people in the vehicle.