What is the formula to calculate density and units?
Density = Mass/Volume.
Conversion between units will depend on what the two units are.
Volume = Mass/Density.So, if you know the density in terms of pounds per barrel, simply divide the mass by the density. If not, either use dimensional analysis to convert the density from the given units to pounds per barrel, or calculate the volume in the units used for the density and then conversion to barrels.