Chemistry solving for volume?

I am having troubles solving this problem, if you could show your work and explain what you did would be great. Magnesium (Mg) is a valuable metal used in alloys, in batteries, and in chemical synthesis. It is obtained mostly from seawater, which contains about 1.3g of Mg for every kilogram of seawater. Calculate the volume of seawater (in liters) needed to extract 8.0X10^4 tons of Mg. which is roughly the annual production in the us. (density of seawater = 1.03g/ml. If you can help me that would be great, thanks.