Aunt Zhang bought a box of Fuji apples at the wholesale market for 52.8 yuan, took them to her small fruit shop, and sold them at a price of 5 yuan per kilogram. How much did she earn after a box of apples was sold out?
张阿姨在批发市场买了一箱富士苹果，花了52.8元，拿到她的小水果店，以每千克5元的价格出售，一箱苹果卖完后，她赚了多少钱？
<gadget id="calculator">15 * 5</gadget>
<output>75</output>

<gadget id="calculator">75 - 52.8</gadget>
<output>22.2</output>

<result>22.2</result>