This book contains an Excel-based solution to this problem, applying principles of the authors, 'profit system model' of the firm that enables forecasts of trends in sales, expenditures, profits and other business variables. The program, called FIRM, which runs on Windows with Microsoft Excel 2010, useshistorical time series of total sales, total costs, and total assets of the firm from its financial statements (income statements and balance sheets), estimates relationships among these variables, and then employs the estimated relationships to forecasts trends in these vital business variables. Featuring step-by-step case examples, the goal is to equip business managers and students with easy-to-use tools for understanding and forecasting trends in important business variables, thereby empowering them to make better business decisions.