How can I calculate multiple items?

I need to be able to calculate an item which if multiples of the same item are added, there is a discount.

Example, we drive passengers. If we have a party of 2+passengers they get a discount. Its $43 for the first passenger, and an additional $33 for the second, and an additional $20 for the 3rd passenger. If there are 4+ passengers they are $15 each... 

If you have configured the items using one of our payment integrations, you can set a special pricing for the items based on the quantity.

https://www.jotform.com/help/265-What-is-Special-Pricing

If the items are configured using our basic fields like the radio button or checkbox or dropdown, you can get the result by conditional calculation:

https://www.jotform.com/help/268-Conditional-Logic-Inserts-Text-Calculation-Into-A-Field

Please try it and let us know if you need further assistance.