X-Axis

The X-axis on a graph plots the independent variable.

If you wanted to see how the cost of labor effects profit, the cost of labor would be the independent variable. The higher the cost of labor, the lower the profit would be. Therefore the profit depends on the cost of labor; it is the independent variable plotted on the X axis.

https://accounting.uworld.com/cpa-review/lc/accounting-dictionary/term/x-axis/