Explanation:

total revenue from operations Rs 9,00,000; Cash revenue from operations Rs 3,00,000; Debtors Rs 1,00,000; B/R Rs 20,000

credit revenue from operations i.ie. Net credit sales =  Total revenue from operations - Cash revenue from operations 

                                                                                   = Rs. 9,00,000 - Rs.3,00,000

                                                                                   = Rs. 6,00,000

                                        average trade receivables =Rs 1,00,000 + Rs 20,000 = Rs.1,20,000 

Note : In this opening & closing balances of debtors & bills receivable are not given, so given values will be taken as              Average values

Trade Receivables Turnover Ratio = credit revenue from operations/average trade receivables

                                                       =  Rs. 6,00,000/Rs.1,20,000

                                                      = 5 times