From city A to city B, it takes 10 hours for the fast train to complete the journey (assuming the speed remains constant), and 15 hours for the slow train to complete the journey (assuming the speed remains the same). The cities are opposite each other, and the express train traveled 180 kilometers when they met. How many kilometers are the distance between A and B?
从A城到B城，快车行完全程需10时，(假设行驶速度始终不变)，慢车行完全程需15时(假设行驶速度始终不变)，现两车同时从A、B两城相对开出，相遇时快车行了180千米，A、B两城相距多少千米？
<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">1 / 15</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">(1/10) + (1/15)</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">1 / (1/6)</gadget>
<output>6</output>

<gadget id="calculator">(1/10) * 6</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">180 / (3/5)</gadget>
<output>300</output>

<result>300</result>