human
Joy has 30 pencils, and Colleen has 50 pencils. If they bought the pencils at $4 each at the store, how much more money did Colleen pay than Joy for her pencils?
assistant
How many pencils does Colleen have more than Joy? ** The number of pencils that Colleen has more than Joy is 50-30 = <<50-30=20>>20 pencils.
How much more money did Colleen pay than Joy for her pencils? ** If each pencil was sold at $4 each, Colleen paid $4*20 = $<<4*20=80>>80 more for the 20 extra pencils she has more than Joy.
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