Before talking scripts, we have to talk about your data model.
You need a table where each Pipline section and the fees for each form a separate record. Do you have that?
Then you can compute the total charge for a particular delivery in a different related table where you specify the volume delivered. A join table would also be needed where you "build" the list of selected Pipeline sections needed for a given delivery.
And this is just the start. Additional tables and relationships are also likely to be needed--especially if specific "deliveries" are a repeating event--perhaps with variations in the precise volume delivered.
I'm thinking in terms of this:
Customers::__pkCustomerID = DeliveryInvoice::_fkCustomerID
DeliveryInvoice::__pkDelInvoiceID = DeliveryRoute::_fkDelInvoiceID
PipeLineSections::__pkPipeID = DeliveryRoute::_fkPipeID
Note, that this is essentially the same structure as is typical of any sales invoice system:
But instead of a lineItems table that lists individual items purchased, we have sections of PipeLine through which a given delivery may be routed. Thus, you may find it helpful to examine the invoice starter solution that comes with your copy of either FIleMaker 11 or FileMaker 12.
For an explanation of the notation that I am using, see the first post of: Common Forum Relationship and Field Notations Explained
Thank Phil for ur expedit reply. I am still new to filemaker. Will give a try tonight.