Problem adding numbers in List Created

I am writing a simple iOS app to let people know their rating and how that rating increases or decreases with each game they play.

But I am having difficulty with what should be a simple task.

I've tried everything, like

playerGrade = playerGrade + PointsGained

but to no avail. I have sort of tried to set up an array which appends the value of PointsGained to a file which I can post process but this is difficult as well.

Does anyone have any ideas?

When I implements this simple task it comes up with an error that the compiler can't process the types in sufficient time.

Thanks,

Dave

Problem adding numbers in List Created
 
 
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