I need some help writing the necessary javascript to achieve the following in RSForsPro.

I have a fairly complex form with a number of conditional fields. I'm fine with all that and really like the way RSForms!Pro handles this.

However, I'm having one small problem.

The form is for school events and there is a cost per pupil. This cost changes depending on the venue - I can do this bit with conditional fields. But I need to be able to show a field for the number of students (at Price A or Price B, depending on venue). And then have the form calculate the final cost.

The process goes like this:

select venue 1 which displays a field further down the form that displays the cost per student = price A

Booker enters number of students and the form calculates
number of students x price A = TOTAL

or

select venue 2 which opens field that shows cost per student = price B
Booker enters number of students and form calculates
number of students x price B = TOTAL

Once all that has been created correctly, the form will send a PDF Invoice.

Can anyone please help me with the conditional calculation part?

Thanks in advance, David

Have you tested to use one the examples on RSForm Pro demo site
http://demo.rsjoomla.com/calculation-form-example

or from the documentation
http://www.rsjoomla.com/support/documentation/view-article/89-simple-calculation-with-rsformpro.html

Matt