I need your help. I don't understand on this one. Would you explanation to me? I would be great appreciated:) Thank you.

• A stock is currently selling for $45 a share. What is the gain or loss on the following transactions?
• a. You take a long position and the stocks price declines to $41.50.
• b. You sell the stock short and the price declines to $41.50.
• c. You take a long position and the price rises to $54.
• d. You sell the stock short and the price rises to $54.