Error "global name nights is not defined"


What could be the problem as I keep getting this error " plane_ride_cost('Charlotte') raised an error: global name 'nights' is not defined" 
def hotel_cost(nights):
    return 140 * nights
def plane_ride_cost(city):
    if city == "Charlotte":
        return 183 * nights
    elif city == "Tampa":
        return 220 * nights
    elif city == "Pittsburgh":
        return 222 * nights
def rental_car_cost(days):
    rent= days * 40
    if days >=7:
        rent= rent-50
    elif days >=3:
        rent= rent-20
    return rent
def trip_cost(city, days):
    return rental_car_cost(days) + hotel_cost(days) + plane_ride_cost(city)


You use the nights variable in your function plane_ride_costs but nights is not defined in this function.
And you only need to return the number, no calculation needed in plane_ride_cost.


the prices for the places are fixed, they don't need to be multiplied with nights


After removing the multiplication with the nights the error I am getting is : plane_ride_cost('Los Angeles') returned None instead of the correct value 475


you forgot to add a elif to check if city could be Los Angeles


Thanks guys, the code is running perfectly now