a boy paid 36 cents for marbles. he lost three and then sold 1/3 of the remainder at cost for 90 cents. how many marbles did he buy originally?

Jody bought 20 shares of amazon at the close price of $121.00. she bought 20 more shares a year later at the price of $127.00. two years later, she sold all of her shares at the price of $133.00. her broker charges $50 for each transaction. after all of these transactions, how much money did jody make?