Two cars, A and B, are traveling towards each other from AB at the same time. Car A encounters Car B at the end of the journey (7/12). Find the speed of car A in kilometers for the remaining distance.
甲乙两辆汽车同时从AB两地相向而行，甲车行完全程的(7/12)时与乙车相遇，相遇后乙车继续以每小时40千米的速度前进，用4.2小时行完余下路程，求甲车的速度是多少千米．
<gadget id="calculator">40 * 4.2</gadget>
<output>168</output>

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

<gadget id="calculator">168 / (7/12)</gadget>
<output>288</output>

<gadget id="calculator">288 - 168</gadget>
<output>120</output>

<gadget id="calculator">120 / 40</gadget>
<output>3</output>

<gadget id="calculator">168 / 3</gadget>
<output>56</output>

<result>56</result>