Widget formula help: Count of Open Activities against a team for Open Requests of Type Problem

[Berto2002]

I seek a count of the number of Open Activities (Tasks) that a team has against Open Problem Records (assigned to any team); in a widget. I cannot work out how to use two different tables in the widget.

In the Reports, I have this configured as Table selection:

Column Selection:

Which gives me the list of tasks for a given team