Calculating Relative Motion on a Moving Sidewalk

[SgtSniper90]

Homework Statement

When the moving sidewalk at the airport is broken, as it often seems to be, it takes you 54 s to walk from your gate to baggage claim. When it is working and you stand on the moving sidewalk the entire way, without walking, it takes 72 s to travel the same distance.
How long will it take you to travel from the gate to baggage claim if you walk while riding on the moving sidewalk?

Homework Equations

v=v'+V (they are vectors)

The Attempt at a Solution

I try to set up the equation but i can't seem to figure out what v and v' are so i try to add and subtract the obvious numbers but i can't seem to get the right answer.

 

[PhanthomJay]

What's the person's speed when walking a distance L, and what's the person's speed when not walking while standing on the moving sisdewalk, over that same distance? You must list what you think are the relevant equations, and show some attempt at a solution, for further assistance.