The homeowner is worried about the work needed to maintain a grass lawn and flower beds, so she is now looking at some low-maintenance materials. She is considering artificial turf, which costs $15 per square foot to install, and gravel, which costs $3 per square foot. She may use a combination of the two materials in different parts of the yard.

Her budget is still $3,000.

Here is a graph representing some constraints in this situation.

The graph shows a line going through `(500,100)`. In this situation, what does the point `(500,100)` mean?