An investor bought a stock on margin. The margin requirement was $60\%,$ the current price of the stock is $$80,$ and the stock price was $$50$ one year ago. If margin interest is $5\%,$ how much equity did the investor have in the investment at year$-$end?

A$)73\mathrm{.}8\%.$

$($B$)60\mathrm{.}6\%.$

C$)67\mathrm{.}7\%.$