I assume each person in the group must have 1 pencil AND 1 eraser each.
Since you have more pencils than erasers, then the limiting factor is the number of erasers. So a group of 56 people will have 1 pencil And 1 eraser and Clare will have 24 pencils left over (assuming Clare has her own pencil and eraser - if not then the group size is 55 assuming Clare is not in the group)
