I understand that scatter plots allow trendlines over multiple data series within the same chart.
However, scatter plots do not allow x-axis labels to be populated with text.
So, I have used a line chart (which allows text x-axis labels, e.g. January, February, etc), that has two data series.
How can I create a trendline in a line chart that combines the data from both series, the same way this is possible in a scatter plot?