Posted by Zachary on Wednesday, January 14, 2009 at 10:33pm.
of ten boxes, five contain pencils, four contain pens, and two contain both pencils and pens. How many boxes are empty??

algebra  Ms. Sue, Wednesday, January 14, 2009 at 10:38pm
Your question isn't clear.
Evidently, the two containing both pencils and pens are included in the first part of the question. Therefore, only one box may be empty. 
algebra  Gen, Friday, October 21, 2011 at 8:48am
Or is it possible the two that contain pens and pencils can kind of cross over. 3 boxes Pens only, 2 boxes pencils only, 2 boxes pens and pencils combined. So that would leave 3 boxes empty ? That would also work out to 5 boxes with pens, 4 boxes with pencils and 2 with both and remain under 10.