Lexi, Lauren and Madeleine wrapped up their discussion with a view of how to calculate the weighted average cost of capital. Lexi says, One should always use accounting-based future information to value debt and equity to determine the weights for different sources of capital. Madi disagreed, you should always use the book-value (historical-based) information to value the elements in the sources of capital. Lauren said no, you should use market-based values of debt equity where you can. Who is correct? Support your answer with examples, as appropriate.