Problem 11.12 Consider a portfolio set up by buying one call, selling short one put, and lending KDisc(r,Tt) cash with risk-free rate, at time t with maturity at time T. Let the strike price of the put and call be K and maturity time T. Show that the value of the portfolio is the value S of the underlying asset and use it to prove the put-call-parity equation. Problem 11.12 Consider a portfolio set up by buying one call, selling short one put, and lending KDisc(r,Tt) cash with risk-free rate, at time t with maturity at time T. Let the strike price of the put and call be K and maturity time T. Show that the value of the portfolio is the value S of the underlying asset and use it to prove the put-call-parity equation