Rice is 2.40 yuan per kilogram, and flour is 1.80 yuan per kilogram. Xiaohua takes 100 yuan to buy 10 kilograms of rice and 10 kilograms of flour each. How much should I get back?
大米每千克2.40元，面粉每千克1.80元．小华拿100元钱去买大米和面粉各10千克，应找回多少元？
<gadget id="calculator">2.4 * 10</gadget>
<output>24</output>

<gadget id="calculator">1.8 * 10</gadget>
<output>18</output>

<gadget id="calculator">24 + 18</gadget>
<output>42</output>

<gadget id="calculator">100 - 42</gadget>
<output>58</output>

<result>58</result>