Mom bought 8.5 kilograms of rice, 2.6 yuan per kilogram of rice. Mom paid the salesperson 30 yuan, how much should I get back?
妈妈买了8.5千克大米，每千克大米2.6元．妈妈付给售货员30元，应找回几元？
<gadget id="calculator">30 - 22.1</gadget>
<output>7.9</output>

<result>7.9</result>