$(15)$ If you long a European call at $$120,$ and short a European put at $$80.$

$($a$)(10)$ What is the portfolio payoff at expiry if the security price at expiry is $$70?$ What is the payoff if the security price at expiry is $$110?$

$($b$)(5)$ Plot the portfolio payoff at expiry as a function of the security price level at expiry.