Two cars leave from Yibin and Chengdu at the same time. It takes 4 hours for car A to drive from Yibin to Chengdu, and 3 hours for car B to drive from Chengdu to Yibin. After how many hours do the two cars meet?
两辆汽车同时从宜宾和成都相对开出，甲车从宜宾开往成都需要4小时，乙车从成都开往宜宾需要3小时，经过几小时两车相遇？
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

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

<gadget id="calculator">(1/4) + (1/3)</gadget>
<output>7/12 = around 0.583333</output>

<gadget id="calculator">1 / (7/12)</gadget>
<output>12/7 = around 1.714286</output>

<result>12/7 = around 1.714286</result>