Let the cumulative normal distribution function. Rewrite the Black–Scholes formula for the value of a European call in terms of . This is the way the Black–Scholes formula is written in finance...

Let

the cumulative normal distribution function. Rewrite the Black–Scholes formula for the value of a European call in terms of . This is the way the Black–Scholes formula is written in finance books.

A European put that gives one the option to sell a share of stock at price K at time t_E
has value

at time t_E. Find the present-day value of the European put at time 0.