On a map with a scale of 1:4,000,000, the distance between ports A and B is 9 cm. A freighter sails from port A to port B at a speed of 30 kilometers per hour at 6 am. The time to arrive at port B is how long
在比例尺是1：4000000的地图上，量得A、B两港距离为9厘米，一艘货轮上午6时以每小时30千米的速度从A港开向B港，到达B港的时间是多少时
<gadget id="calculator">1 / 4_000_000</gadget>
<output>1/4_000_000 = around 0</output>

<gadget id="calculator">9 / (1/4_000_000) / 100_000 / 30</gadget>
<output>12</output>

<gadget id="calculator">6 + 12</gadget>
<output>18</output>

<result>18</result>