Ao Zebra and Koizumi travel from City A to City B. It is known that their speeds are the same, both are 25 km/h, and at 12:00 noon, Koizumi has traveled 5 times as far as O'Zebra; at 2 o'clock in the afternoon, Koizumi has traveled three times as far as O'Zebra. So, how many hours earlier did Koizumi set off than O'Zebra?
奥斑马、小泉从甲城前往乙城．已知他们的速度相同，都是25千米/时，且中午12点时，小泉已行的路程是奥斑马的5倍；下午2点时，小泉已行的路程是奥斑马的3倍．那么，小泉比奥斑马早出发多少小时．
<gadget id="calculator">2 * 4</gadget>
<output>8</output>

<result>8</result>