I have the following linear programming model:

$\displaystyle p = 10x+15y$

Constraints:

$\displaystyle 1x+2y \le 600$

$\displaystyle 0.125x+0.5y \le 100$

$\displaystyle 0.05x+\frac{1}{3}y \le 60$

$\displaystyle 0 \le x\le 500$

The constraint I'm struggling with is the last one (about x's maximum value).

I've been taught to solve them by plotting the points. When you plot the points, the x value is always greater than 500 (in this case, 600,800 and 1200).

What is the appropriate course of action here? Do I just assume $\displaystyle x$ is 500, or do I need to do something else?

Thank you in advance