In this question,it is given that,
The volume v of a pyramid with a square base with side length s and height h is
[tex]V = \frac{1}{3} s^2 h[/tex]
And we have to solve for s.
First we will get rid of 3 by multiplying both sides by 3, that is
[tex]3V = s^2h \\ s^2 = \frac{3V}{h} \\ s = \sqrt{ \frac{3V}{h}}[/tex]
And in the next part it is given that , volume is 7700 cubic meters and height is 148 meters .
Substituting these values, we will get
[tex]s = \sqrt{ \frac{3V}{h}} \\ s = \sqrt{ \frac{3*7700}{148}} = 12.5 meters[/tex]