For this case we have that by definition of power properties it is fulfilled that:

Then, if we have the following expression:

Applying the property, we can rewrite the expression as:

Answer:

Check the picture below.
the "lateral" area, or "sides" area, is just the area of all the four triangular faces, and it doesn't include the bottom or base of the pyramid.
however, notice, each triangular face is really just a triangle with a base of 24, and a height of 16.
It mostly depends on what operation you are doing.