You do not need to worry about the common denominator since both fractions share the denominator of 3. All you have to do is subtract. Personally for me, I like dealing with improper fractions not mixed fractions.
Part 1. First convert both fractions to improper fractions. To do this you multiply the denominator to the whole number at the side then add the numerator. From there you will have a value that you use to replace the numerator. Keep the denominator as 3.
you multiply the length and height, then, you figure out what you multiply to get the volume by dividing the product of the length and height multiplied.
