Average value from 2 different period of time

[#1]

Hello community,

I am new in Qlikview and I need some help to obtain the following calculation:

Objective: To calculate revenue per customer

1. For each month I need the average balance:

[End-of-month balance (current month) + End-of-month balance (previous month)] /2

I have all the balances per month and per customer in one table

2. Multiply the average times a monthly fee (% for each customer  which I have in another table)

The challenge is that I need to do all of this on the script for the Revenue to be a new field called “Revenue” and have this field on each month…..