Two cars, A and B, start from the same place at the same time and drive towards each other. After 2.4 hours, the distance between them is 216 kilometers. The speed of car A is 42 kilometers per hour. Find the speed of car B? (column equation solution)
甲、乙两辆汽车同时从同一地点出发，相背而行，2.4小时后相距216千米，甲车的速度是每小时42千米，求乙车的速度？(列方程解答)
<gadget id="calculator">42 * 2.4</gadget>
<output>100.8</output>

<gadget id="calculator">216 - 100.8</gadget>
<output>115.2</output>

<gadget id="calculator">115.2 / 2.4</gadget>
<output>48</output>

<result>48</result>