-- Look for a common factor of both the top and bottom numbers.
==> 5 is a common factor of 45 and 100 .
-- Divide the top and bottom numbers by their common factor.
==> 45/100 = 9/20 .
-- Look for another common factor of both the top and bottom numbers.
==> The only common factor now is ' 1 ' .
==> That means the fraction is now as simplified as it can get.