How can I create a form calculation for biliary surgeries?

How would I do something like this: 

How many biliary surgeries do you do a month? 250 is the answer. The cost of bleeding could be 250 x .15 (15%) x $300 (cost per bleeding complication) = (the app would need to provide the answer)

It seems to me that you are trying to create a form that can calculate the cost of bleeding per complication.

I would suggest referring to this guide here https://www.jotform.com/help/259-How-to-Perform-Calculation-in-the-Form and you could then have your fields assigned to input those values with the total answer as your output.

You can also refer to this guide here https://www.jotform.com/help/267-Form-Calculation-Math-Function-Reference for additional references for functions since you want to use a percentage.