Click on Open, locate the Chapter9.Xamarin solution, and open it.
The Solution Explorer should look like this:
Now, control (^) + click on the Chapter9.Xamarin label and select Add | New Project.
In the New Project dialog box, scroll down the left-hand pane until you see the Multi Platform section.
Click on Library and select .NET Standard Library under General in the right-hand pane. Also make sure C# is selected:
Click ...
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