Please solve using excel, thanks!

1. a. Shares of EXAM Corp. are trading at $50. The stock does not pay dividends. The price of a three-month put with an exercise price of $50 is currently $4 (per share). If the risk-free rate of interest is 10%, calculate the price of an "at the money" call (with a strike price also of $50)? b. If you believe that EXAM Corp. shares will continue to trade close to $50 for the next three months, what would be a simple options strategy using a put and a call to profit from your conviction? What is the most money you could make from it? How far can the stock move in either direction before you lose money