I am afraid the image shows two series -- bar and line. Still, I can confirm -- it is possible to add 3 chart series be it 3 bar series, 2 bar series and one line, etc. Just follow the guidlines provided by Peter.
Note, that there is a limitation you must be aware of -- the chart item can only have 2 Y axes - a primary and a secondary, so when you add 3 series you will have to choose one of these for each of them, there is no way to have 3 Y axes.
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