When adding fractions, the denominators need to be the same, but you can’t add the denominators to get the answer. Simply put, if the denominators are already the same, the fractions are simple to add, such as 1/3 + 1/3 = (1 + 1)/3 = 2/3. If the denominators are not the same, find the common denominator by multiplication. For example, 1/2 + 1/3 + 3/6 + 2/6 = (3 + 2)/6 = 5/6.

When subtracting fractions, the denominators again need to be the same; and you can’t add (or subtract) the denominators to get the answer. If the denominators are the same, subtract the fractions, such as 2/3 - 1/3 = (2 - 1)/3 = 1/3. If the denominators are not the same, find the common denominator by multiplication, such as ½ -1/3 = 3/6 - 2/6 = (3 - 2)/6 = 1/6.