I have a table with three related fields. Field1 is the total of a bill (currency). Field2 is a portion of the bill for customer A (20% of the value of field1, or one fifth). Field3 is a portion of the bill for customer B (40% or two fifth). I have all three fields in the add page. My idea is that I will only populate field1 in the add page. Field2 and field3 will then be filled automatically accordingly. Could someone help me with any codes? Thank you.