investment analysis question

3. Buck Ewing opened a margin account at a local brokerage firm. Buck's initial in- vestment was to purchase 200 shares of Woodbury Corporation on margin at $40 per share. Buck borrowed $3,000 from a broker to complete the purchase. a. At the time of the purchase, what was the collateral in Buck's account? b. If Woodbury stock subsequently rises in price to $60 per share, what is the col- lateral in Buck's account? c. If Woodbury stock subsequently falls in price to $35 per share, what is the col- lateral in Buck's account