the simple interest on a certain sum for 5 years at 11% per annum is $640 less then the simple interest on the same sum for 7 years at 9% per annum. find the sum

How to do this , and can some one explain

Which statement about 6x2 + 7x – 10 is true?

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?