laramie trucking's ceo is considering a change to the company's capital structure, which currently consists of 25% debt and 75% equity. the cfo believes the firm should use more debt, but the ceo is reluctant to increase the debt ratio. the risk-free rate, rrf, is 5.0%, the market risk premium, rpm, is 6.0%, and the firm's tax rate is 25%. currently, the cost of equity, rs, is 11.5% as determined by the capm. what would be the estimated cost of equity if the firm used 60% debt? (hint: you must first find the current beta and then the unlevered beta to solve the problem.) a. 13.58% b. 11.50% c. 16.05% d. 12.50% e. 14.77%