4.(Functions) > Taking a vacation > 4.(Transportation)

Oops, try again. It looks like rental_car_cost returns None instead of the correct amount (40) for 1 days. But it's working for more than a day.

I expect for for 1 day to have a return of 40.

```
def rental_car_cost(d):
rentcost = d * 40
if d >= 7:
rentcost-=50
return(rentcost)
elif d >= 3 and d < 7:
rentcost-=20
return(rentcost)
rental_car_cost(4)
```

EDIT ;

Found what my error is, it was a stupid one, I wasn't considerating rentals lasting less than 3 days.

Fixed with

```
else:
return(d * 40)
```