The road between A and B is 540 km long. Two passenger and freight vehicles travel towards each other from A and B at the same time. If the passenger vehicle completes the journey in 6 hours, the truck completes the journey in 9 hours. How many hours later will the two cars meet on the way?
A、B两地之间的公路长540千米．客货两车同时从A、B两地相向而行，若客车6小时行完全程，货车9小时行完全程．多少小时后两车在途中相遇？
<gadget id="calculator">1 / 6</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">1 / 9</gadget>
<output>1/9 = around 0.111111</output>

<gadget id="calculator">(1/6) + (1/9)</gadget>
<output>5/18 = around 0.277778</output>

<gadget id="calculator">1 / (5/18)</gadget>
<output>18/5 = around 3.6</output>

<result>18/5 = around 3.6</result>