Look at the fraction problem below:

In this example, the denominators are not the same. To subtract these two fractions, first you must change them to equivalent fractions with the same denominator. To do this, find the LCD, the smallest number that is a multiple of both of the denominators.
Let's look at our fraction problem again:

In this problem, 6 is the Least Common Denominator:

Now it's time to add the LCD to our problem. The Least Common Denominator will replace the original denominators. Look at the original problem again:

The first fraction in the problem already has the LCD as its denominator. It does not need to change.
To change



Let's see what our problem looks like with these changes:

We're ready to solve our new fraction problem. Now that the denominators are the same, we simply subtract using the two numerators:

Our answer is:

Don't forget to simplify your answers when you can. Divide the numerator and denominator by their GCF.

Our simplified answer is:
