You invested in $150$ shares of a technology company's common stock on margin at $$60$ per share. The initial margin requirement is $60\%,$ and the stock does not pay dividends. Calculate the maintenance margin at which a margin call will occur if the stock price drops to $$40$ per share.

$0\mathrm{.}33$

$0\mathrm{.}25$

$0\mathrm{.}40$

$0\mathrm{.}55$

$0\mathrm{.}23$