<human>:  Liam and Mitchell own competing lemonade stands across the street from one another. When Liam bragged that he had made $63 one weekend, Mitchell laughed and told Liam he had sold 21 lemonades at $4 apiece the same weekend. How many more dollars did Mitchell make selling lemonade that weekend than Liam?
<bot>: How much money did Mitchell make selling lemonade? ** Mitchell made 21 * 4 = $<<21*4=84>>84 selling lemonade.
How many more dollars did Mitchell make selling lemonade than Liam? ** Thus, Mitchell made 84 - 63 = $<<84-63=21>>21 more selling lemonade that weekend than Liam.
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