```
def hotel_cost(nights):
return 140 * nights
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
def rental_car_cost(days):
cost == 40 * days
if days >= 7:
cost -= 50
elif days >= 3 and days <= 7:
cost -= 20
else:
return cost
None
Oops, try again. An error was raised for rental_car_cost(1): local variable 'cost' referenced before assignment
I have no idea what I am doing wrong, if someone could please help me to understand what is going wrong. Help a pal out... Thanks.
```

# Transportation

**baileymh880**#1

**stetim94**#2

this line:

`cost == 40 * days`

what is it suppose to do? (yes, i know what its suppose to do, but i would like to hear it from you)

**baileymh880**#3

It means the cost of the rental car is equal to how many days the car is rented multiplied by the cost of the car ($40).

**stetim94**#4

but cost is not yet defined, so how can it equal something?

usually we use is equal inside conditions (like `if`

and `elif`

), but in your case its not a condition?

The purpose of your function is to calculate how much it would cost to rent the car for `x`

days.This means you need to calculate the $40 * days, then apply discount, then return the total cost for renting a car

**stetim94**#6

i edited my earlier answer

So it would make sense to multiply $40 * days, and then store this in a variable. Then we can see if we need to apply discount, then finally we can return cost

If you need more help, post an updated version of your code

**system**#7

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