A ship travels 12.5 kilometers per hour and reaches its destination in 42 hours. If it travels 15 kilometers per hour, how many hours can it arrive in advance?
一艘船每小时行12.5千米，42小时到达目的地，如果每小时行15千米，可以提前几小时到达？
<gadget id="calculator">42 / 15</gadget>
<output>14/5 = around 2.8</output>

<gadget id="calculator">12.5 * (14/5)</gadget>
<output>35</output>

<gadget id="calculator">42 - 35</gadget>
<output>7</output>

<result>7</result>