Williamsen GmbH has a debt to equity ratio of $2\mathrm{.}5.$ The firm$$s weighted average cost of capital is $15$ per cent, and its cost of debt is $10$ per cent. Suppose that there is no corporate tax.

a$)$ What is Williamsen$$s cost of equity capital?

b$)$ What is Williamsen$$s unlevered cost of equity capital?

c$)$ What would Williamsen$$s weighted average cost of capital be if the firm was

unlevered?