Hi

I am struggling with oulling it all together. i am sure i need to double the days. but the Def creates a problem. can someone point out what i am doing incorrectly.

My code is below

```
def hotel_cost(nights):
costs = 140*nights
print costs
return hotel_cost(5)
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
print plane_ride_cost(Tampa)
def rental_car_cost(days):
costs = 40*days
if days >= 7:
costs -=50
elif days >=3:
costs -=20
return costs
def trip_cost(city, days):
def double(days):
return 2 * days
def trip_cost (a, b):'
return double(a) +city("Charlotte")
```