Urgent algebra help!
posted by Caroleen .
Here's my question. Please walk me through it so I can fully understand it.
Jon begins jogging at a steady 3 meters/sec down the middle of Lane #1 of a public track. Laaura starts even with him in the center of Lane #2 but moves at 4 meters/sec. At the instant they begin, Ellis is located 100 meters down the track in Lane #4, and is headed toward them in his lane at 6 meters/sec. After how many seconds will the runners lie in a straight line?
a. Let t be the number of seconds the three have been running. Write expressions for the number of meters each has run after t seconds.
b. Consider the location of each runner as a point on a graph. What quantity might you use as the xcoordinate? What quantity might you use as the ycoordinate?
c. How can you tell if three points are on a line? Use this to solve the problem.
Any help is appreciated, even if you can only solve one part. Thank you!

I answered this yesterday. Did you read my answer?

No, I never got to. I'm sorry about that! I guess it would be a few pages back, then?
Thank you very much! I'll respond again or post another message if I have any other problems with your response. 
My previous answer can be found at at
http://www.jiskha.com/display.cgi?id=1231284425 
Thank you so much! You were a great help.