You see the various Units Sold charts such as Units Sold by Segments and Units Sold by Country.
Tap, hold, drag, and drop one chart on top of another to merge the two charts.
Note:
Prior to merge, you can predict if the merge will be successful. If a merge is going to be successful, then you see a green background color for the drop target; else, you see a red background color for the drop target.
You see a new combination chart to work with like other charts.