An amusement park charges a $20 admission fee and $3 for each ride. Which equation can be used to determine c, the total cost of a day at the amusement park, based on n, the number of rides?
n = 3c + 20
n = 20c +3
c = 3n + 20
c = 20n + 3
Every ride adds $3, so for n rides you pay 3n. There is only one answer that has 3n in it. And it is the correct one because it adds the fixed $20 for admission.
