Car A and car B drove from Rugao to Nanjing successively at the same speed. At 8:30 in the morning, car A was still 168 kilometers away from Nanjing, and car B was still 150 kilometers away from Nanjing; The distance to Nanjing is 4 times that of car B from Nanjing. At this time, how many kilometers is car B from Nanjing?
甲、乙两辆汽车用同样的速度先后从如皋开往南京，上午8：30，甲车离南京还有168千米，乙车离南京还有150千米；上午10时整，甲车距离南京的路程是乙车距离南京路程的4倍．此时，乙车离南京还有多少千米？
<gadget id="calculator">168 - 150</gadget>
<output>18</output>

<gadget id="calculator">4 - 1</gadget>
<output>3</output>

<gadget id="calculator">18 / 3</gadget>
<output>6</output>

<result>6</result>