The distance between A and B is 20.4 kilometers, A's speed is 4 kilometers per hour, B is 1.2 kilometers faster than A, A starts from A, and B starts from B after 0.5 hours. After another 1.5 hours, C starts from A by car, and the three meet at the same place. Ask for C's speed?
AB相距20.4千米，甲的时速是4千米，乙比甲快1.2千米，甲从A出发，0.5小时后乙从B出发．又过1.5小时丙开车从A出发，三人在同一地点相遇，求丙的速度？
<gadget id="calculator">4 * 0.5</gadget>
<output>2</output>

<gadget id="calculator">20.4 - 2</gadget>
<output>18.4</output>

<gadget id="calculator">4 + 1.2</gadget>
<output>5.2</output>

<gadget id="calculator">4 + 5.2</gadget>
<output>9.2</output>

<gadget id="calculator">18.4 / 9.2</gadget>
<output>2</output>

<gadget id="calculator">0.5 + 2</gadget>
<output>2.5</output>

<gadget id="calculator">2 - 2</gadget>
<output>0</output>

<gadget id="calculator">0.5 + 0</gadget>
<output>0.5</output>

<gadget id="calculator">4 / 0.5</gadget>
<output>8</output>

<gadget id="calculator">2.5 * 8</gadget>
<output>20</output>

<result>20</result>