The supermarket bought a box of bananas weighing 20 kilograms in the wholesale market and spent 50 yuan. Then sell it at 5 yuan per kilogram. After a box of bananas is sold out, how much money do you make?
超市在批发市场进了一箱重20千克的香蕉，花了50元．然后以每千克5元的出售，一箱香蕉卖完后，赚了多少钱？
<gadget id="calculator">20 * 5</gadget>
<output>100</output>

<gadget id="calculator">100 - 50</gadget>
<output>50</output>

<result>50</result>