Consider a European put and a European call option which are both written on a non-dividend paying stock, have the same strike price K = 80 and expire in T = 2 months. These options are trading for p = 21 and c = 30.80, respectively. The underlying stock price is S₀ = 90. The continuously compounded risk-free rate of interest is r = 10% per annum.

What is the present value of the arbitrage profit? In your response, please show all cash flows (both today and at expiration) and explain why this is an arbitrage (i.e. risk-less) profit.