Zhao Yu's family drove from Beijing to Beidaihe during the summer vacation. It took 4 hours to go, with an average of 87 kilometers per hour. When I came back, due to the traffic jam, I lost an average of 29 kilometers per hour. How many hours can reach Beijing?
赵宇一家暑假期间自驾车从北京出发去北戴河游玩．去时用了4小时，平均每小时行驶87千米．回来时由于堵车，平均每小时少行驶29千米．几小时可以到达北京？
<gadget id="calculator">87 - 29</gadget>
<output>58</output>

<gadget id="calculator">4 / 58</gadget>
<output>2/29 = around 0.068966</output>

<gadget id="calculator">87 * (2/29)</gadget>
<output>6</output>

<result>6</result>