gain on stock

can someone explain how to calculate net gain/loss until now on a stock for a specific period( say 1 month). The daily buy /sell price and quantities are given.  

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wouldn’t that be the HPY ?

hashtag wrote:

Suppose you buy 10 grams of coke at $65/gram, then re-sell it to some guys looking to have fun at a party for $85/gram. 

What’s your net gain?


if i sell and buy quantities of the stock in between the the above two transactions, wouldn’t it affect the net gain/loss ? ( i need the gain @ 85 by your example)