Rajan Inc has a debt$-$equity ratio of $2\mathrm{.}5.$ The firm$$s weighted average cost of

capital is $15$ percent, and its pretax cost of debt is $10$ percent. Rajan is subject

to a corporate tax rate of $35$ percent.

$($a$)$ What is Rajan$$s cost of equity capital?

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

$($c$)$ What would Rajan$$s weighted average cost of capital be if the firm$$s

debt$-$equity ratio were $0\mathrm{.}75?$

$($d$)$ What would Rajan$$s weighted average cost of capital be if the firm$$s

debt$-$equity ratio were $1\mathrm{.}5?$