How do you identify the slope and y intercept with the equation y=-3x+4

What is the slope of the equation y =

Credit card a offers an introductory apr of 3.4% for the first three months and standard apr of 15.7% thereafter,

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?