Can you solve this everyday practical math problem?

Many supermarkets have cart storage areas in their parking lots. Suppose you want to minimize the distance that you walk. Assume that the cart storage area is in the same parking column as your car. You have the option of getting the cart from the storage area or the store and returning the cart to either the storage area or the store. How do you decide?

The case where the storage area is between the car and the store is fairly easy. Always return the cart to the storage area. It makes no difference where you get it from.

What should you do if the storage area is between the car and the store, and what does it depend on? Your intuition may be able to guide you. I found it convenient to have a variable for the distance from the car to the storage area and another one for the distance from the car to the store.