Consider the following binomial tree.

The numbers in squares are stock prices. The numbers in circles will be option prices (# numbers are the exercise numbers to answer your calculation). Today, the stock is at 100 and can go up and down over the next week, and then again up and down from there. We are pricing a call struck at 90. Delta is .75

1. What is today's call premium?

2. If you sell a call option on one hundred shares, the delta hedge will require you to buy how many shares of stock?