A ship departs from a port 240 nautical miles away and reaches the destination 48 nautical miles away. The speed is reduced by 10 nautical miles per hour. The total time after arrival is equal to the time spent on the whole journey after the original speed is reduced by 4 nautical miles per hour. Find the original speed.
一船向相距240海里的某港出发，到达目的地前48海里处，速度每小时减少10海里，到达后所用的全部时间与原速度每小时减少4海里航行全程所用的时间相等，求原来的速度．
<gadget id="calculator">8 - 3</gadget>
<output>5</output>

<gadget id="calculator">10 / 5</gadget>
<output>2</output>

<gadget id="calculator">2 * 8</gadget>
<output>16</output>

<result>16</result>