I think you're going to need to create another table that acts as a rollup to get this to work
Try this:
1. Create a new table called "Summary" or some such
2. In your original table, create a new linked field to the "Summary" table
3. Click the field header of your "Date" field. This should select all the values in this column
4. Click the field header of the newly created linked field from step 2
5. Paste the values in
6. In the "Summary" table, a whole bunch of new records should have been created, with each record representing a single date
7. Create a "Count" field to get the number of jobs per date
8. Create a "Currency" field to input the flat rate for that day, e.g. 500
9. Create a "Formula" field to divide the rate by the number of jobs
You should be able to apply the same logic for the urban and long distance problem