Setting Calculations on an editable PDF

There are many ways to do this. If one looks at any text field's property, there is a tab labeled "Calculations" where one can enter the code to perform the calculation for that field. There are 3 options, select the fields & operation, Simplified Field Notation, and Custom JavaScript. Each method uses a different approach for entering the calculation but ultimately the calculation is all done by JavaScript. Also all methods require the use of specific field names. It is even possible to compute all the values in the grand total field and if coded n a certain way one does not need to know the number of rows to be calculated.  It is also important to select the correct format for the fields. Since all your basic calculations will involve multiplying and summing numbers, I would format all the fields being used as "Number" and set the correct number of decimal places for the displayed result. Note that the format adjust the value of the field to display a specified number of decimal places. This can be different from the actual result of the calculation. This situation becomes very apparent in calculating tax amounts.

For a specific answer we will need to know the name of the fields being used in your calculations.

For the easiest approach one should plan the field names so one can if needed calculate detailed field name to be used in a calculation.

See: https://acrobatusers.com/tutorials/how-to-do-not-so-simple-form-calculations