Uncle Zhang in the cafeteria bought 3.5 kilograms of beans at the vegetable market and gave it to the salesperson for 10 yuan, and got back 3.7 yuan. How much is it per kilogram of beans?
食堂张叔叔在菜市场买了3.5千克豆角交给售货员10元，找回3.7元，每千克豆角多少钱？
<gadget id="calculator">10 - 3.7</gadget>
<output>6.3</output>

<gadget id="calculator">6.3 / 3.5</gadget>
<output>1.8</output>

<result>1.8</result>