Assignment of receivables would mean sale of the lease rentals, not the asset. In that case, the leased asset still remains the property of the assignor – that is, the assignor has retained the residual interest in the asset. However, it would be different if the lessor sells the asset that has been leased out.
Average accounts receivable is calculated as the sum of starting and ending receivables over a set period of time (generally monthly, quarterly or annually), divided by two.
Gross accounts receivable represents the total amount of outstanding invoices or the sum owed by customers. It's perhaps the easiest to calculate, too - you simply add up all the outstanding invoices at a given time!
Average accounts receivable is calculated as the sum of starting and ending receivables over a set period of time (generally monthly, quarterly or annually), divided by two. In financial modeling, the accounts receivable turnover ratio is used to make balance sheet forecasts.