It takes 4 hours for a passenger car to drive from A to B, and 6 hours for a truck to drive from B to A. The passenger and freight vehicles leave from A and B respectively at the same time. After how many hours can they meet?
客车从甲地开往乙地需要行驶4小时，货车从乙地开往甲地要行驶6小时，客、货两车同时分别从甲、乙两地相向开出，经过几小时可以相遇？
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 / 6</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">(1/4) + (1/6)</gadget>
<output>5/12 = around 0.416667</output>

<gadget id="calculator">1 / (5/12)</gadget>
<output>12/5 = around 2.4</output>

<result>12/5 = around 2.4</result>