I am still kind of confused about this topic and I want to review it. How do I solve the following?

PROBLEM 1: Alabasta Company determined that the net realizable value of its accounts receivable at December 31, 2020, based on an aging of the receivables, was P365,625. Additional information is as follows: Allowance for uncollectible P33,750 accounts - 1/1/20 Uncollectible accounts written 20,250 off during 2020 Uncollectible accounts 2,250 recovered during 2020 Accounts receivable at 13/31/20 393,750 For 2020, what would be Alabasta's uncollectible accounts expense?PROBLEM 2: Accounts receivable - net of P50,000 P10,000 credit balance in customer's accounts Notes receivable (trade) 5,000 Notes receivable (non-trade), 25,000 P5,000 collectible within one year Dividends receivable 1,000 Subscription receivable, due 2,000 within one year Advances to officers and 4,000 employees, due in 18 months Accounts payable - net of P6,000 3,000 debit balance in suppliers' accounts Information from the records of Skypeia is shown above. 1. How much is the total trade receivables? 2. How much is the total trade and other receivables to be reported in the statement of financial position?PROBLEM 3: Accounts receivable, 1/1/19 P650,000 Credit sales for 2019 2,700,000 Sales returns for 2019 75,000 Accounts written off during 40,000 2019 Collection from customers 2,150,000 during 2019 Estimated future sales returns 50,000 at 12/31/19 Estimated uncollectible 110,000 accounts at 12/31/19 The following information relates to Zou Co's account receivable for 2019: 1. What amount should Zou report for accounts receivable, before allowances, at December 31, 2019? 2. How much is the doubtful expense in 2019? 3. What is the net realizable value of the accounts receivable at December 31, 2019