Lisa, Jack, and Tommy earned $60 from washing cars all week. However, half of the $60 was earned by Lisa. Tommy earned half of what Lisa earned. How much more money did Lisa earn than Tommy?
Lisa earned $60 * 1/2 = $<<60*1/2=30>>30.
Tommy earned $30 * 1/2 = $<<30*1/2=15>>15.
Lisa earned $30 - $15 = $<<30-15=15>>15 more than Tommy.
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