Mixing Solutions - Calculating Water Content

During a science experiment, a student mixes two solutions. The first solution is $\frac{2}{5}$ of a liter of water, and the second solution is 0.8 liters of saltwater. After mixing both solutions, how much of the mixture is water?

To solve this, remember to first convert all quantities to a common unit. The total quantity of water used in the mixture is your answer.