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? Let's think first. Chain of thought:
The number of pencils that Colleen has more than Joy is 50 - 30 = 20 pencils. If each pencil was sold at $4 each, Colleen paid $4 * 20 = $80 more for the 20 extra pencils she has more than Joy.
Therefore, the answer is 80.