Dad used a fruit warehouse with a monthly rent of 600 yuan, and stored 3 tons of fruit. By convention, these fruits need to be sold for two months. As a result of lowering the sales price, it was sold out in one month. Due to the savings in rent, after the settlement, I earned an extra 60 yuan. How much is it lower than planned per kilogram of fruit in sales?
爸爸以每月600元的租金用了一个果品仓库，存放进去3吨水果．按照惯例，这些水果需销售两个月．由于降低了销售价格，结果1个月就销售完了．由于节省了租金，结算下来，反而多赚了60元．销售时每千克水果比计划降低了多少元？
<gadget id="calculator">600 - 60</gadget>
<output>540</output>

<gadget id="calculator">3 * 1_000</gadget>
<output>3_000</output>

<gadget id="calculator">540 / 3_000</gadget>
<output>9/50 = around 0.18</output>

<result>9/50 = around 0.18</result>