A kind of fruit is 3.8 yuan per kilogram, and the mother brings 20 yuan to buy 2.5 kilograms of this kind of fruit, how much should I get back?
一种水果每千克3.8元，妈妈带20元钱买2.5千克这样的水果，应找回多少元？
<gadget id="calculator">2.5 * 3.8</gadget>
<output>9.5</output>

<gadget id="calculator">20 - 9.5</gadget>
<output>10.5</output>

<result>10.5</result>