What is another way to write 5 + 5 + 5 using a different operation?

Explain how you can use the associative property to evaluate (7x50)x4.

Could someone me with this question i’ve been stuck on it for 20 minutes

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?