Add extra value after selection an option

I'm looking to create values in which someone can choose three options for a price, with an additional 40 dollar charge for each item chosen after that. Can someone help me with that?

Hi,

What you have read is just the first step. Which is assigning values to your options.

Second thing you need to do is, add the Form Calculation widget. Then, add your Radio Field or Your option fields.

From there, create the formula to add 40 on your options. Just like this.

Take a look at my example here.