Originally Posted by

**shadow6** Mary is playing golf. The diagram below describes her situation. Determine the equation of this relation. Then find the time when the ball is 20m away from the hole.

What I did so far was the following:

Find *a* using P(0, 15) and s = -50, t = 50 into y=a(x-s)(x-t).

15 = a(0-(-50))(0-50)

15 = a(50)(-50)

15 = 2500a

3/500 = a

Therefore the equation of this relation is y = 3/500(x+50)(x-50)

Now the problem is, I'm not sure how to find the time. Do I substitute 20m into the above equation? Also, what units would the time be in?