Use the equation of the line of best fit, y=3.90x+15.40, to answer the questions below.
Give exact answers, not rounded approximations.
(a) What is the predicted midterm score for a student who doesn't spend any time studying?

(b) What is the predicted midterm score for a student who studies for 15 hours?
(c) For an increase of one hour in the time spent studying, what is the predicted increase in the midterm score?