Two ships A and B are traveling towards each other from two ports at the same time. Ship A travels 25 kilometers per hour, and car B travels 20 kilometers per hour. The two ships meet at a distance of 15 kilometers from the midpoint. How many hours did it take for the two ships to meet after they sailed out at the same time? (Note: Requires two different approaches to answer)
甲乙两艘轮船同时从两个港口相向而行，甲船每小时行25千米，乙车每小时行20千米．两船在距离中点15千米处相遇．两船同时开出后经过多少小时相遇？(注意：要求用两种不同的方法解答)
<gadget id="calculator">25 - 20</gadget>
<output>5</output>

<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">15 * (2/5)</gadget>
<output>6</output>

<result>6</result>