Keep getting that error message and I don't know where I wen't wrong... someone please help me...

# Vacation Trip Spending Estimator

# Cost of Hotel Stay

def hotel_cost(nights):

return 140 * nights

# Cost of plane tickets

print "Plane Ticket Prices"

city = str(raw_input("What city are you visiting? "))

# Function Defines Checks to Make Sure

# The user entered a string

def plane_ride_cost(city):

if city == "Charlotte":

return 183

elif city == "Tampa":

return 220

elif city == "Pittsburgh":

return 222

elif city == "Los Angeles":

return 475

else:

return "City not found"

# This function is to calculate the cost of the Rental Car

# For the duration of the trip

days = raw_input("How many days do you need the Rental car? ")

def rental_car_cost(days):

cost = days * 40

if days >= 7:

cost = cost - 50

return cost

elif days >= 3:

cost = cost - 20

return cost

else:

return days * 40

# This function is to add everything together

def trip_cost(city, days, spending_money):

return rental_car_cost(days) + hotel_cost(days) + plane_ride_cost(city) + spending_money