It takes 6 hours for a passenger car to go from city A to city B, and 7 hours for a truck to travel from city B to city A. The two cars leave from the two cities at the same time. After 2 hours, the distance between the two cars is still 160 kilometers. What is the distance between the two cities? km?
客车从甲城到乙城需要6小时，货车从乙城到甲城需要7小时，两车同时从两城相向开出，2小时后两车还相距160千米，甲、乙两城相距多少千米？
<gadget id="calculator">1 / 6</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">1 / 7</gadget>
<output>1/7 = around 0.142857</output>

<gadget id="calculator">(1/6) + (1/7)</gadget>
<output>13/42 = around 0.309524</output>

<gadget id="calculator">(13/42) * 2</gadget>
<output>13/21 = around 0.619048</output>

<gadget id="calculator">1 - (13/21)</gadget>
<output>8/21 = around 0.380952</output>

<gadget id="calculator">160 / (8/21)</gadget>
<output>420</output>

<result>420</result>