Additional Series on two x

[Felix]

I have a simple columns chart with two series stacked on top of each other.
(different colors with values inside)

I would like to add a third series in form if a line which would be the
total of the two values

Can I do this and how? Thank you

 

[Wigi]

First calculate the values for that 3rd series (the sum of the other 2 series).

Then plot the series on the chart.

Then click the 3rd series in the chart and change the series to a line.