python-2.7 - Python での総コストの計算

Question

Python で旅行プランナーを作成しようとしていますが、すべての関数を定義した後、最後の関数でそれらを呼び出して計算することができませんtripCost()。

tripCost に、日数と旅行先 (都市) を入力すると、プログラムが関数を実行し、前に定義した 3 つの関数すべての正確な結果が得られます。

コード：

def hotelCost(): 
    days = raw_input ("How many nights will you stay at the hotel?")
    total = 140 * int(days) print "The total cost is",total,"dollars"


def planeRideCost(): 
    city = raw_input ("Wich city will you travel to\n")
    if city == 'Charlotte':
        return "The cost is 183$"
    elif city == 'Tampa':
        return "The cost is 220$"
    elif city == 'Pittsburgh':
        return "The cost is 222$"
    elif city == 'Los Angeles':
        return "The cost is 475$"
    else:
        return "That's not a valid destination"

def rentalCarCost(): 
    rental_days = raw_input ("How many days will you rent the car\n")   
    discount_3 = 40 * int(rental_days) * 0.2 
    discount_7 = 40 * int(rental_days) * 0.5 
    total_rent3 = 40 * int(rental_days) - discount_3
    total_rent7 = 40 * int(rental_days) - discount_7
    cost_day = 40 * int(rental_days) 

    if int(rental_days) >= 3: 
        print "The total cost is", total_rent3, "dollars"
    elif int(rental_days) >= 7: 
        print "The total cost is", total_rent7, "dollars"
    else: 
        print "The total cost is", cost_day, "dollars"

def tripCost():
    travel_city = raw_input ("What's our destination\n")
    days_travel = raw_input ("\nHow many days will you stay\n")
    total_trip_cost = hotelCost(int(day_travel)) + planeRideCost (str(travel_city)) + rentalCost (int(days_travel))
    return "The total cost with the trip is", total_trip_cost

tripCost()