Can someone please explain what this basic problem statement means?

Here is the entire problem if it helps but I'm really just looking for clarification on the statement below as it seems like it is the key for solving the problem.

http://imgur.com/a/k5vOD

For setting operating parameters such as x, the mass fraction of water in product, the relative impact of two streams - the product and the recycle - is considered in a rudimentary economic analysis. The selling price of the product is fixed at $120 per metric ton of product and the cost of pumping the recycle is $50 per metric ton of recycle. A simple objective function based on the profit i.e. sales minus the cost can then be used.