Here are book and market value balance sheets of the United Frypan Company (UF): Assume that MM's theory holds with taxes. There is no growth, and the $40 of debt is expected to be permanent. Assume a 40% corporate tax rate. a. How much of the firm's value is accounted for by the debt-generated tax shield? b. How much better off will UF's shareholders be if the firm borrows $20 more and uses it to repurchase stock?