After being the CFO of Mullen Inc. for over $10$ years, you start your own company to directly compete with Mullen. You want to use Mullen$$s information to estimate your company$$s cost of capital. Mullen has $30,000$ common stocks outstanding with a price of $$10\mathrm{.}3$ per share. The current dividend is $$1\mathrm{.}5$ per share and will grow at $3\%$ per year. The market risk premium is $10\%$ and the risk$-$free rate is $4\%.$Mullen also finances its operations with two bonds. The first bond has $$80,000$ par value, $15\%$ coupon rate, $12$ years to maturity, and is trading at $120(120\%$ of par$).$ The second bond has $$60,000$ par value, $10\%$ coupon rate, $15$ years to maturity, and is trading at YTM of $13\mathrm{.}5\%.$ All bonds pay semi$-$annual coupons. The tax rate is $30\%.$

a$)$ Calculate the beta and Mullen's cost of equity.