Question 739885
If the tank is a rectangular prism with those measurements, its volume is
{{{(3m)(2.5m)(80m)=600m^3}}}
Maybe 600 cubic meters would be accepted as an answer.
If an answer in liters were expected, remember that:
1mL is 1cm^3 (or as a nurse would say 1cc)
1L is 1dm^3
1000L is 1m^3
so the volume of the tank, in liters is 600,000L.