A portfolio manager wrote $90$ MAY $700$ OEX calls $.$ On the expiration date, the S&P $100$ index is at $675\mathrm{.}00.$ a$.)$ What is the amount the portfolio manager must pay to the holder of the OEX options $?$ b$.)$ What is the amount the portfolio manager would have had to have paid if the S&P $100$ index had finished at $705?$