I’m working on a finance multi-part question and need a sample draft to help me learn.

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**An investor for a firm buys a call on ABC stock with a strike price of K and writes a put with the same strike price and maturity. Assuming the options are European and that there are no dividends expected during the life of the underlying, how much should such a portfolio cost?** **A stock is currently trading at 80. Your firm holds a portfolio consisting of the following:**

Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â (**a) Long 100 units of stock.**

**Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â (b) Short 100 calls, each with a strike of 90.**

**Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â (c) Long 100 puts, each with a strike of 70.**

**Suppose the delta of the 90-strike call is 0.45 while the delta of the 70-strike put is -0.60. What is the aggregate delta of this portfolio? We consider each component of the portfolio individually, and then add them up.Â **

**A stock is currently trading at 80. There are one-month calls and puts on the stock with strike prices of 70, 75, 80, 85, and 90. The price and delta of each of these options is given below:**

**Strike: 70 / 75 / 80 / 85 / 90**

**Call Price: 10.60 / 6.47 / 3.39 / 1.50 / 0.56**

**Put Price: 0.30 / 1.15 / 3.05 / 6.14 / 10.18**

**Call Delta 0.92 / 0.77 / 0.54 / 0.31 / 0.14**

**Put Delta: -0.08 / -0.23 / -0.46/ -0.69 / -0.86**

For each of the following portfolios:

(a) Long 100 units of stock, short 100 units of the 80-strike call.

**Find the current value of the portfolio****Find the approximate value of the portfolio following a $1 decrease in the stock price.**

(b) Long 1000 units of the 80-strike call and 1174 units of the 80-strike put.

**Find the current value of the portfolio****Find the approximate value of the portfolio following a $1 decrease in the stock price.Â**