If you are trying to get the simplest form of a fraction, then you look and find a number that can be multiplied by any number to get each part of the fraction. Once you have found that number, you divide both numbers by that number and the quotient of both is your answer.
Examples: 10/20=1/2 because 10 goes into 20 2 times
9/12=3/4 because 3 goes into 9 3 times and 12 4 times
