This article explains how to add a secondary axis to a chart in Excel so you can view unlike categories on the same graph. These instructions work in Excel in Microsoft 365, Excel 2021, Excel 2019 ...

How Excel Charts Work A chart has an x-axis range and a y-axis range to show the correlation between two different data sets. The x-axis is the horizontal category line.

Naming Basics Best practice recommendations are to create a chart placing independent variables on the horizontal, x-axis and dependent variables on the vertical, y-axis.