If d = rt, Then r = d/t
avg speed = 720/t
Therefore after subtracting penalty points, the function for score is:
[tex]s = \frac{720}{t} - p[/tex]
For part 2 i will attach a picture.
Part 3)
Set s = 3 and solve for t
[tex]\frac{720}{t} - 2 = 3[/tex]
[tex]720 = 5t[/tex]
[tex]t =144[/tex]