If you buy a stock at a current price, then buy more at another. what price is it at?

meaning for example: like if I buy 100 shares of a stock at 20$. then the stock goes down to say 15$. then I buy another 100 shares at 15$. Does that mean I have 100 shares at 20$ and 100 shares of the same stock at 15$? Does the also mean if I sell I would see 100shares at 20 and 100shares at 15?
4 answers 4