Uncle Wang bought a box of 20Kg Red Fuji apples at the wholesale market and spent a total of 45 yuan. He took it to his small shop and sold it at 3.2 yuan per Kg. After a box of apples was sold out, how much money did he make?
王伯在批发市场买了一箱20Kg的红富士苹果共花了45元．他拿到他的小店，以每Kg3.2元出售，一箱苹果卖完后，他赚了多少钱？
<gadget id="calculator">3.2 * 20</gadget>
<output>64</output>

<gadget id="calculator">64 - 45</gadget>
<output>19</output>

<result>19</result>