lets use slope-intercept formula, beacuse this problem looks linear.since this is a function we should use f(x) instead of y, so our equation should be f(x) = mx + b (it is usually y = mx+b). our slope would be 1.50 because it increases by a certain amount, and our y intercept would 15, since that is the initial amount, so our equation would be f(x) = 1.50x + 15 ( i think) so to find , lets say how much ten people could ride, then we would do 1.50(5) + 15 ( it is 5 and not 10 because remember 15 for up to and only 5 so just take of 5 from 10 and it five) and your answer would be $22.50 (in dollars) for 10 people.
hope this helps, sorry about the mistakes though.
