Mom took 100 yuan to the supermarket to buy rice and mung beans. First, she bought 25 kilograms of rice at 3.6 yuan per kilogram. The remaining money just bought 2.5 kilograms of mung beans. How much is each kilogram of mung beans?
妈妈拿100元钱到超市买大米和绿豆，先买了25千克大米，每千克3.6元，剩下的钱刚好买了2.5千克绿豆，每千克绿豆多少钱？
<gadget id="calculator">3.6 * 25</gadget>
<output>90</output>

<gadget id="calculator">100 - 90</gadget>
<output>10</output>

<gadget id="calculator">10 / 2.5</gadget>
<output>4</output>

<result>4</result>