Use the Black$$Scholes formula to value the following options:

A call option written on a stock selling for $$77$ per share with a $$77$ exercise price. The stock's standard deviation is $7\%$ per month. The option matures in three months. The risk$-$free interest rate is $1\mathrm{.}50\%$ per month.

A put option written on the same stock at the same time, with the same exercise price and expiration date.

Please calculate a $-$ call value, and b $-$ put value.