Rice is 2.3 yuan per kilogram. Dad bought 25 kilograms of rice and paid 100 yuan. How much money did he get back?
大米每千克2.3元，爸爸买了25千克大米，付出100元，找回多少钱？
<gadget id="calculator">2.3 * 25</gadget>
<output>57.5</output>

<gadget id="calculator">100 - 57.5</gadget>
<output>42.5</output>

<result>42.5</result>