According to the bond$-$yield$-$plus$-$riak$-$permium approach, a finm's cost of retained earnings, rs$,$ can be estimaid by adling a risk premiam of $3$ to $5$ percentape points to is $$

cost of preferred stock, $\frac{t_p}{s}$

risk free rate of return

before$-$tax interest cost of debe, $5,$

return on equity $($ROE$)$

after$-$tax intereat enst of debe, ift