It takes 6 hours for the express train to travel from station A to station B, and 9 hours for the slow train to travel from station B to station A. The two cars depart from the two stations at the same time and meet at a distance of 18 kilometers from the midpoint. How many kilometers are there between A and B?
快车从甲站开往乙站要6小时，慢车从乙站开往甲站需要9小时．两车分别从两站同时开出，在离中点18千米处相遇．甲、乙两站相距多少千米？
<gadget id="calculator">18 * 2</gadget>
<output>36</output>

<gadget id="calculator">1 / 6</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">1 / 9</gadget>
<output>1/9 = around 0.111111</output>

<gadget id="calculator">(1/6) + (1/9)</gadget>
<output>5/18 = around 0.277778</output>

<gadget id="calculator">1 / (5/18)</gadget>
<output>18/5 = around 3.6</output>

<gadget id="calculator">(18/5) * (1/6)</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">(18/5) * (1/9)</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">(3/5) - (2/5)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">36 / (1/5)</gadget>
<output>180</output>

<result>180</result>