Ship A departs from port A and travels 18 kilometers per hour. After 5 hours, ship B catches up with ship A in 9 hours after departure. What is the speed of ship B?
甲船从A港出发，每小时行18千米，5小时后，乙船出发9小时追上甲船，乙船的速度是多少．
<gadget id="calculator">18 * 5</gadget>
<output>90</output>

<gadget id="calculator">90 / 9</gadget>
<output>10</output>

<gadget id="calculator">18 + 10</gadget>
<output>28</output>

<result>28</result>