find volume of this prism

Answer:
[tex]324[/tex] [tex]km^{3}[/tex]
Step-by-step explanation:
V = [tex]\frac{1}{3}[/tex] [tex]b[/tex] · [tex]h[/tex]
V = [tex]\frac{1}{3}[/tex] [tex]81[/tex] · 12
V = [tex]\frac{1}{3}[/tex] [tex]972[/tex]
V = [tex]324[/tex] [tex]km^{3}[/tex]