A car goes from point A to point B. It goes uphill first and then downhill. The uphill speed is 30 kilometers per hour, and the downhill speed is 42 kilometers per hour. From point A to point B, it takes only 2.4 hours to return. Hours, how many kilometers is the distance between AB and AB?
一辆汽车由A地到B地，先上坡后下坡，上坡速度为每小时30千米，下坡速度是每小时42千米，从A地到B地，要三小时返回只要2.4小时，AB相距几千米？
<gadget id="calculator">3 + 2.4</gadget>
<output>5.4</output>

<gadget id="calculator">42 + 30</gadget>
<output>72</output>

<gadget id="calculator">42 / 72</gadget>
<output>7/12 = around 0.583333</output>

<gadget id="calculator">5.4 * (7/12)</gadget>
<output>3.15</output>

<gadget id="calculator">30 * 3.15</gadget>
<output>94.5</output>

<result>94.5</result>