A car travels 242 kilometers in 3 hours. The speed of the first part of the journey is 84 kilometers per hour, the speed of the second part is 76 kilometers per hour, and the speed of the third part is 80 kilometers per hour. It is known that the third part of the journey is 40 kilometers per hour. m, find the time taken for the first segment of the journey.
一辆汽车3小时行程242千米，其中走第一段路程时速84千米，走第二段路程时速76千米，走第三段路程时速80千米，已知第三段路程为40千米，求第一段路程所用的时间．
<gadget id="calculator">3 / 2</gadget>
<output>3/2 = around 1.5</output>

<result>3/2 = around 1.5</result>