Answer:
x = 15
Step-by-step explanation:
The volume (V) of a pyramid is calculated as
V = [tex]\frac{1}{3}[/tex] Ah ( A is the area of the base and h the height )
Here V = 225, A = x² and h = [tex]\frac{1}{5}[/tex] x , thus
[tex]\frac{1}{3}[/tex] × x² × [tex]\frac{1}{5}[/tex] x = 225, that is
[tex]\frac{1}{15}[/tex] x³ = 225 ( multiply both sides by 15 )
x³ = 3375 ( take the cube root of both sides )
x = [tex]\sqrt[3]{3375}[/tex] = 15
