Can any1 help?

answer 12 minutes.(the LCM)

Let's make a slight modification:

Pierre can ride once around the track in 5 minutes.
Louis takes 3 minutes.
How many minutes will it take for Louis to lap Pierre?

Hint: It's not the LCM.

makr, Yes LCM could be a coincidence (I was thinking of bell intervals)

Okay choose a track 30 units long (say).

First speed is 6 units per min, second is 10 units per min. Difference is 4 units per min relative (closing speed assuming first remains stationary)

Second laps first in 30/4 = 7.5 minutes .

"Pierre can ride once around the track "


He will never catch him, it's only a one lap race.

Yep.

If x and y (x < y) are the times per lap, then the faster rider will lap the slower rider in
xy/(y-x) minutes