Three people go to a place 30 kilometers apart at the same time. It is known that the three people walk at the same speed, which is 5 kilometers per hour. Now there is a bicycle, but it can only be ridden by one person. It is known that the speed of the bicycle is 10 kilometers per hour. Let one of them ride the bicycle first, put down the bicycle after reaching a certain place, and continue to move forward; the second person rides on it after arriving, drives for a while, puts it down and lets the third person ride, and continues to move forward, so that the three arrive at the same time Jiadi. Question: How many hours did the three of them spend?
三个人同时前往相距30千米的甲地，已知三人行走的速度相同，都是5千米每小时；现在还有一辆自行车，但只能一个人骑，已知骑车的速度为10千米每小时．现先让其中一人先骑车，到中途某地后将车放下，继续前进；第二个人到达后骑上再行驶一段后又放下让第三个人骑行，自己继续前进，这样三人同时到达甲地．问：三人花的时间为多少小时．
<gadget id="calculator">30 - 10</gadget>
<output>20</output>

<gadget id="calculator">20 / 5</gadget>
<output>4</output>

<gadget id="calculator">4 + 1</gadget>
<output>5</output>

<result>5</result>