An Airplane Has Room for 390 Coach-Fare Seats $x$ Coach-Fare Seats And

Short Answer

An airplane has room for 390 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 $x=0$ , what is the value of $y$ ?