If you graph a linear equation, you can pick any value of x and check the corresponding value in the y-axis through the graph. This way, if we supppose an equation y = 2x, we can pick the numbers:
0, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, and 30, and calculate the value of y for each one, or just see it in the graph, as follows:
If you plot a more detailed graph, it can become even easier to find to solve the question proposed to Max. It is possible to insert gridlines to ease the visualization, as follows:
Answer: Max can pick values in the x-axis and use the gridlines to find the corresponding point in the graph to each x, and from there, use again the gridline to find the value of y associated with that point. This way, Max will be able to find the 15 solutions, which are 15 ordered pairs.