having problems working out these type of questions. could you show work? thanks!!

Sapp Trucking's balance sheet shows a total of noncallable $45 million long-term currently has a market value of $50 million. The balance sheet also shows that the company has 10 million shares of common stock, and the book value of the common equity (common stock plus retained earnings) is $55 million. The current stock price is $20 per share; stockholders' required return, rs, is 16.71%; and the firm's tax rate is 40%. The CFO thinks the WACC should be based on market value weights, but the idiot president thinks book weights are more appropriate. What is the difference between these two WACCs