Put together a Black-Scholes option calculator in Excel to answer the following:

a. What is the call option value with S₀=$45, K=$48, r=6%, T=15 months, and volatility=40%?

b. What is the put option value with S₀=$60, K=$65, r=6%, T=18 months, and volatility=20%?

c. What is the put option value with S₀=$38, K=$40, r=6%, T=3 months, and volatility=60%?

d. What is the call option value with S₀=$100, K=$95, r=8%, T=3 years, and volatility=40%?

When I use this formula it doesn't work.

45*NORM.DIST((LN(45/48)+(6%+0.5*40%^2)*15/12)/(40%*SQRT(15/12)),0,1)-48*EXP(-6%*15/12)*NORM.DIST((LN(45/48)+(6%+0.5*40%^2)*15/12)/(40%*SQRT(15/12))-40%*SQRT(15/12),0,1)