human
Tommy has 13 items in his pencil case. The pens are twice as many as the pencils and there's one eraser. How many pencils are there?
assistant
How many items are there? ** There are 13 items - 1 eraser = <<13-1=12>>12 pens and pencils.
How many pencils are there? ** There are 12 items / 3 = <<12/3=4>>4 pencils.
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