Mom bought 7.5 kilograms of beans, gave the salesperson 40 yuan, got back 4 yuan, how much is it per kilogram of beans?
妈妈买了7.5千克豆角，给了售货员40元，找回4元，每千克豆角多少元？
<gadget id="calculator">40 - 4</gadget>
<output>36</output>

<gadget id="calculator">36 / 7.5</gadget>
<output>4.8</output>

<result>4.8</result>