Please explain to me the eqns and working for : $1.$ BN Enterprises currently has no debt and a $15\mathrm{.}9\%$ cost of equity. The tax rate is $30\%.$ BN plans to issue debt with a cost of $6\mathrm{.}7\%.$ The funds will be used to to repurchases shares with a resultant capital structure of $30\%$ debt? What will BN$\text{'}$s WACC be after the transaction? ANS: $12\mathrm{.}832.$ Smothers Brothers Ltd$.$ is estimating its WACC. The company has collected the following information:

Its MV capital structure consists of $40$ percent debt and $60$ percent common equity.

The company has $20-$year bonds outstanding with a $10\mathrm{.}1\%$ annual coupon that are trading at par. The company$$s tax rate is $33\%.$ The risk$-$free rate is $5\mathrm{.}6\%.$

The market risk premium is $5\%.$ The stock$$s beta is $1\mathrm{.}4.$ What is the company$$s WACC? ANS: $10\mathrm{.}27\%.$