It takes 3 hours for car A to travel from point A to point B, and it takes 4 hours for car B to travel from point B to point A. The two cars start from point A and point B respectively at the same time. How many hours later will they meet?
甲车从A地到B地要行驶3小时，乙车从B地到A地要行驶4小时，两车同时分别从A地和B地出发，几小时后相遇？
<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(1/3) + (1/4)</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>