A and B are walking towards each other from two places 74.4 kilometers apart at the same time, and they meet after 4 hours. It is known that A travels 10.2 kilometers per hour, how many kilometers per hour does B travel?
甲、乙两人同时从相距74.4千米的两地相对而行，经过4小时相遇．已知甲每小时行10.2千米，乙每小时行多少千米？
<gadget id="calculator">74.4 / 4</gadget>
<output>18.6</output>

<gadget id="calculator">18.6 - 10.2</gadget>
<output>8.4</output>

<result>8.4</result>