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You can do this by conditional logic. Here's our guide for the conditional calculation: https://www.jotform.com/help/268-How-to-Insert-Text-or-Mathematical-Caculation-into-a-field-using-a-Condition.
Here's very simple form showing the calculation: https://form.jotform.com/61975747392976. Set date to July 20, 2016, and select "Home" from the Listing.
Here's the conditional logic for that:
Please try that and let us know if you need help setting it up in your form.