An Airplane Has Room for 360 Coach-Fare Seats

An airplane has room for 360 coach-fare seats. It can replace any 3 coach-fare seats with 2 first-class seats. Suppose the airplane is configured with x coach-fare seats and y first-class seats, with no space wasted. If you found a formula for y as a function of x, what would be the significance of the x-intercept?

A) It is the number of first-class seats that could replace one coach seat.
B) It is the number of coach seats that could replace one first-class seat.
C) It is the number of first-class seats, if there are no coach seats.
D) It is the number of coach seats, if there are no first-class seats.