because if its 72 per inch and one column width, you would do 72 times 2 which is 144 and you do the same thing again then add 144 to 144 and you get 288!
A coordinate grid has two perpendicular lines, or axes, labeled like number lines. The horizontal axis is called the x-axis. The vertical axis is called the y-axis. The point where the x-axis and y-axis intersect is called the origin.
