After a truck starts for a while, a passenger car starts from the same starting point to catch up with the truck. It takes 18 minutes for the bus to catch up with the truck. It is known that the distance between the two cars is 2 kilometers in 6 minutes before the bus catches up with the truck. Go after the truck again. How many hours did it take for the passenger car to catch up with the truck for the first time and to catch up with the truck for the second time?
一辆货车出发一段时间后，一辆客车才从同一出发点出发去追上货车．客车用18分钟追上货车，已知客车追上货车前6分钟两车相距2千米，追上后客车立即掉头往回走，6分钟后两车相距12千米，当客车回到出发点后又去追赶货车．客车从第一次追上货车到第二次追上货车一共经过多少小时．
<gadget id="calculator">12 / 6</gadget>
<output>2</output>

<gadget id="calculator">18 * 2</gadget>
<output>36</output>

<gadget id="calculator">2 / 6</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">36 / (1/3)</gadget>
<output>108</output>

<gadget id="calculator">18 + 108</gadget>
<output>126</output>

<gadget id="calculator">126 / 60</gadget>
<output>21/10 = around 2.1</output>

<result>21/10 = around 2.1</result>