Sims company, a service provider, has a normal collection pattern of 24% during the month of service, 51% during the month after service, and 24% in the second month after service. All remaining amounts are uncollectible. On November 1st, Accounts Receivable were $600,900 ($400,000 of this amount related to October sales). November sales are expected to be $800,000. Based on the preceding, September sales were approximately:

please show procedure and explain.