Alright, there are a few problems with your code; The first problem can be found here:

```
if days>=7:
cost -= 50
return cost
elif days>=3:
cost-=20
return cost
```

You have used inconsistent indentation. In Python, where indentation is extremely important, it is highly recommended that you always use 4 spaces of indentation.

The other problem can be found here:

```
def trip_cost(city ,days):
return 140*days + city + cost
```

You are using the variable `cost`

in this calculation. However, `cost`

has neither been defined globally nor within the scope of this function. Also, why are you doing `140 * days`

when you already have a function that does this for you (i.e. `hotel_cost()`

)?

Another issue with this function, is that `city`

cannot be added to `days`

, as `days`

will be an integer and `city`

will be a string. Besides, we don’t want to add `city`

to these other numbers anyway, we want the cost of the plane ride to `city`

, which is why we made a function earlier called `plane_ride_cost()`

.

Lastly, you don’t need to add days to the function, but you **do** need to add the cost for renting a car for `days`

. You made a function for this as well, it’s called `rental_car_cost()`

.

Therefore, the function should actually look like this:

```
def trip_cost(city, days):
return hotel_cost(days) + plane_ride_cost(city) + rental_car_cost(days)
```