b9241

Hello, i'm confused about this subject. I know if I sell some stock, I'm going to be charged capital gains tax, or income tax depending on how long I hold onto the tax. I know they take the price I paid for the stock, (say $100), and then minus it from what I sell the stock at ($120). I would be responsible for paying tax on the $20 gained. What if I purchased the same stock multiple times during different price points? What if I first paid $93.21, then a week later I bought more shares at $96.12, then a month later $98.31? How would this be calculated then?