"Assume zero rates and no dividends, the forward price is $$100.$ If a put at $K=110$ is quoted for $$9,$ you can lock in an arbitrage profit by $("$long$"$n or "short" ${?}^n$ the forward at $K=110$ to receive dollars and $("$buy$"$n or "sell"$\text{'})$ the put at $K=110$ for dollars $"$