train of trucks and a train of passenger cars depart from cities A and B at the same time. When the passenger train completes the journey (7/12), it encounters the truck. The truck continues to drive forward at the original speed of 40 kilometers per hour. Hours to finish the rest of the journey. Find the speed of the bus.
一列货车和一列客车，同时从甲乙两个城市相对开出，客车行完全程的(7/12)时，与货车相遇，货车继续以原来每小时40千米的速度向前开去，用3.5小时行完余下的路程．求客车的速度．
<gadget id="calculator">7 / 12</gadget>
<output>7/12 = around 0.583333</output>

<gadget id="calculator">3.5 / (7/12)</gadget>
<output>6</output>

<gadget id="calculator">40 * 6</gadget>
<output>240</output>

<gadget id="calculator">1 - (7/12)</gadget>
<output>5/12 = around 0.416667</output>

<gadget id="calculator">(5/12) / 40</gadget>
<output>1/96 = around 0.010417</output>

<gadget id="calculator">240 * (1/96)</gadget>
<output>5/2 = around 2.5</output>

<gadget id="calculator">(7/12) / (5/2)</gadget>
<output>7/30 = around 0.233333</output>

<gadget id="calculator">240 * (7/30)</gadget>
<output>56</output>

<result>56</result>