S.O.S. Mathematics CyberBoard

i have a rectangle and i want the time needed for a person to walk on it with uniform speed. a professor told me that i have to divide the rectangle to several small equal shapes but i don't know why?
sorry for my bad english.

plz help me all my work is on hold because of it.

I don't understand what that is supposed to mean.

_________________
The greater danger for most of us lies not in setting our aim too high and falling short; but in setting our aim too low, and achieving our mark. - Michelangelo Buonarroti

i mean if an object is moving on a rectangle with constant speed how can i calculate the time from the start of moving the target untill it reaches a certain point on the rectangle