Corporate Finance and Accounting

I need to write a business letter for Corporate Finance.  It needs to include cause and effect of business transactions and the impact on cash balances.  I need to explain the interralationship of sales,cashflow, accounts receivable and payable.   Why cash can go down even when sales are up.  Which three accounts should CFO review each day and why.  I need to focus on short-term Balance Sheet accounts (receivable and Payablees) and I must have at least 1 citation.