How can I add a fee to my calculation field based on conditional logic?

I have created a form and want to add a $7.00 parking fee based on an individual's parking preference.  I have tried to use required condition, I have tried to make the default answer selected, and I have tried to add to the calculation field through conditions.  I am clearly missing something.  Is there a easy way to accomplish this task? This seems like it should be simple. I cannot get the default on the parking field to hold.

Thank you for contacting us.

The Parking Fee option is affected by 'Clear a field on hide' option on your form.

You might consider using calculation values instead.

You might also need to disable Autofill option on form.

And change selected Quantity to 1 to get instant calculations.

If you need any further assistance on this, please let us know. We will be happy to help.

Thanks for the response.  Great solution!  I was making it too complicated.

We're glad to hear that Mike's solution fixed your issue. Let us know if you need any help. Thank you.