Subtracting Fractions with Different Denominators
To Subtract Fractions with different denominators:
 Find the Lowest Common Denominator (LCD) of the fractions
 Rename the fractions to have the LCD
 Subtract the numerators of the fractions
 The difference will be the numerator and the LCD will be the denominator of the
answer.
 Simplify the Fraction
Example: Find the difference between 3/12 and 2/9.
 Determine the Greatest Common Factor of 12 and 9 which is 3
 Either multiply the numbers and divide by the GCF (9*12=108, 108/3=36)
 OR  Divide one of the numbers by the GCF and multiply the answer times the other
number (12/3=4, 9*4=36)
 Rename the fractions to use the Lowest Common Denominator (3/12=9/36, 2/9=8/36)
 The result is 9/36  8/36
 Subtract the numerators and put the difference over the LCD = 1/36
 Simplify the fraction if possible. In this case it is not possible

