The fast, medium and slow cars are chasing one car. The fast car catches up in 6 hours, the medium car catches up in 10 hours, and the slow car in 12 hours. It is known that the fast car travels 24 kilometers per hour, and the medium car travels 20 kilometers per hour. , so how many kilometers per hour does the slow train travel?
快、中、慢三车去追一辆车，快车6小时追到，中车10小时追到，慢车12小时追到，已知快车每小时行24千米，中车每小时行20千米，那么慢车每小时行多少千米？
<gadget id="calculator">200 - 144</gadget>
<output>56</output>

<gadget id="calculator">56 / 4</gadget>
<output>14</output>

<gadget id="calculator">14 * 6</gadget>
<output>84</output>

<gadget id="calculator">144 - 84</gadget>
<output>60</output>

<gadget id="calculator">60 / 12</gadget>
<output>5</output>

<gadget id="calculator">5 + 14</gadget>
<output>19</output>

<result>19</result>