Can you ever have more individuals on a higher level in a food chain than a lower level? why?

No because there will not be a large enough supply of lower-level species to feed all of the higher level species, so the lower level will run out, meaning the higher level will have no food and also die.

The perimeter of a rectangle doesn't tell you its dimensions, so there are
an infinite number of different dimensions and different areas it could have
with the same perimeter.  I'm pretty sure there's some more information in
the part of the question that you skipped over before you started copying
the part that you posted.