If Lucy would give Linda $5, Lucy would have the same amount of money as Linda. If Lucy originally had $20, how much money did Linda have at the beginning?
After giving $5, Lucy has $20 - $5 = $
<gadget id="calculator">20-5</gadget>
<output>15</output>
15 left.
Since Linda has $15 after receiving $5, then she had $15 - $5 = $
<gadget id="calculator">15-5</gadget>
<output>10</output>
10 at the beginning.

<result>10</result>