I need to create an equation (or more than one) in order to update values (currency) with a specific indexer. The idea is to insert every month new index and the system will update specific fields values (currency) with this indexer. The valeu to be updated will have a start term and end term (sometimes it will be current day). So the equation needs to multiply a value by the index of the last month and divide the result by the index of starting term month. For example, US$ 10,00 in march 2016 and the system should update it to december 2016. The equation should be US$ 10,00 * (march 2016 index) / (december 2016).
Anyone have any idea on how can I create this equation?