$[2-$S$01$:$30]$ A stock price can go up by $20\%$ or down by $15\%$ over the next year. The current stock price is greater than $70.$ You own a one$-$year put on the stock. The put has an exercise price of $78\mathrm{.}26.$ The effective annual risk$-$free interest rate is $11\mathrm{.}25\%.$

The stock pays no dividends.

If the put is exercised today, the amount received will be $x.$ The price of the put today $($unexercised$)$ is also $x.$

Calculate the current stock price.