The price of potatoes is 2.4 yuan per kilogram, and a vegetable farmer discounted the original price in order to let the citizens buy more. Knowing that buying 25 kilograms will cost 6 yuan less, ask the vegetable farmer at what percentage of the original price to sell it?
土豆每千克售价2.4元，一菜农为了让市民多买货，把原价打了折扣．已知买25千克就少花6元，问这个菜农按原价的百分之几出售？
<gadget id="calculator">2.4 * 25</gadget>
<output>60</output>

<gadget id="calculator">60 - 6</gadget>
<output>54</output>

<gadget id="calculator">54 / 60</gadget>
<output>9/10 = around 0.9</output>

<result>9/10 = around 0.9</result>