Answer:
The required expression for the volume of pyramid is 
Step-by-step explanation:
Consider the provided information.
A pyramid has a square base with side s. The height of the pyramid is 2/3 that of its side.
The volume of pyramid is: 
Where, l is base length, w is base width and h is the height.
It is given that the base is square therefore, l=s and w=s.
The height of pyramid is 
Substitute the respective values in the above formula.


Hence, the required expression for the volume of pyramid is 