The distance between Jinghong and Kunming is 540 kilometers, and the two cars depart from opposite places. After 6 hours, the distance between the two cars is still the whole distance (2/9). It is known that car A travels 39 kilometers per hour, and car B travels per hour. How many kilometers?
景洪至昆明相距540千米，两车分别从两地相对开出，6小时后两车还相距全程的(2/9)，已知甲车每小时行39千米，乙车每小时行多少千米？
<gadget id="calculator">2 / 9</gadget>
<output>2/9 = around 0.222222</output>

<gadget id="calculator">1 - (2/9)</gadget>
<output>7/9 = around 0.777778</output>

<gadget id="calculator">(7/9) / 6</gadget>
<output>7/54 = around 0.12963</output>

<gadget id="calculator">540 * (7/54)</gadget>
<output>70</output>

<gadget id="calculator">70 - 39</gadget>
<output>31</output>

<result>31</result>