The fast, medium and slow cars start from place A at the same time to catch up with the cyclist in front, and take 6 minutes, 12 minutes, and 20 minutes to catch up respectively. It is known that the fast car travels 24 kilometers per hour, and the medium car travels 20 kilometers per hour. meters, find how many kilometers per hour the slow train travels.
快、中、慢三辆车同时从甲地出发追赶前方的骑车人，分别用6分钟、12分钟、20分钟追上，已知快车每小时行24千米，中车每小时行20千米，求慢车每小时行多少千米．
<gadget id="calculator">24 - 20</gadget>
<output>4</output>

<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(1/5) - (1/10)</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">(1/10) / (1/10)</gadget>
<output>1</output>

<gadget id="calculator">4 * 1</gadget>
<output>4</output>

<gadget id="calculator">20 - 4</gadget>
<output>16</output>

<gadget id="calculator">24 - 16</gadget>
<output>8</output>

<gadget id="calculator">8 * (1/10)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">(4/5) / (1/3)</gadget>
<output>12/5 = around 2.4</output>

<gadget id="calculator">16 + (12/5)</gadget>
<output>92/5 = around 18.4</output>

<result>92/5 = around 18.4</result>