How can I create the math I need?

My company is making a customer contract form. I am trying to figure out how to make it automatically add prices of additional services onto a final service price when a given box is checked.

For example:

Our sales representative will autopopulate parts of the form and send it to the customer partially filled out. (contact information, service price) The customer then has the opportunity to select additional services within the form that were not previously quoted. Ideally, the customer checks the additional services they wish to add, and the form will automatically add preset values specific to each service to the final service price quoted at the bottom. 

If this is possible, is it possible to easily edit the values that are added?

When you look at the form I have linked, the area I wish to be checked it under "Would you like to add additional services?" and after you check yes, the additional services pop up. I would like those fields to add a pre-populated "Agreed Upon Service Price" at the bottom. 

Thank you!

I think you may add a calculation value to each product in your form, here is a guide that will help you with that: How-to-Assign-Calculation-Value

Then once you have added the calculation values you will be able to get this value set and then calculate the amount, to achieve this you will need to add the Form Calculation widget and then calculate the total amount there, here is a guide that will help you to perform calculation in your form: How-to-Perform-Calculation-in-the-Form

Once you do that, new selected options will be automatically added to the total amount, with this calculated you will need to pass the value to your payment integration, here is a guide that will help you with that: How-to-pass-a-calculation-to-a-payment-field

By the way, I noticed that you're asking for CC details through plain text fields, please remove those fields since it goes against our terms, please use one of our existing payment processing apps: https://apps.jotform.com/category/payment_processing 

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