How do you calculate the companies preliminary net income (Step by step by identifying what is a asset/ liability and the calculation itself. Also I need help (step by step) with calculating the companies net profit margin expressed as a percent and why I got that question wrong

No Date General Journal Debit Credit 1 February 01 200 Rent Expense Cash 200 N February 04 800 Cash Service Revenue 800 3 February 07 900 Cash Service Revenue 900 4 February 10 1,200 Salaries and Wages Expense Cash 1,200 5 February 14 100 Advertising Expense Cash 100 6 February 18 Cash Accounts Receivable Service Revenue 500 1,200 1,700 7 February 25 1,350 Supplies Accounts Payable 1,350 Rowland & Sons Air Transport Service, Incorporated, has been in operation for three years. The following transactions occurred in February: February 1 Paid $200 for rent of hangar space in February. February 4 Received customer payment of $800 to ship several items to Philadelphia nex month. February 7 Flew cargo from Denver to Dallas; the customer paid in full ($900 cash). February 10 Incurred and paid $1,200 in pilot wages for flying in February. February 14 Paid $100 for an advertisement run in the local paper on February 14. February 18 Flew cargo for two customers from Dallas to Albuquerque for $1,700; one customer paid $500 cash and the other asked to be billed $1,200. February 25 Purchased on account $1,350 in supplies for future use on the planes. Required: 1. Prepare accrual basis journal entries for each transaction. 2. Calculate the company's preliminary net income. 3. Calculate the company's net profit margin expressed as a percent