a$)$ Astock has expected return of $10\%$ and a beta of $0\mathrm{.}70.$ Assume the risk$-$free rate is $5\mathrm{.}5\%.$ what must the expected return on the market be$?$ b$)$ A stock has expected return of $15\%,$ its beta is $1\mathrm{.}45,$ and the expected return on the market is $12\%.$ What must the risk$-$free rate be$?$