It takes 10 hours for the fast train to travel from A to B, and 15 hours for the slow train to travel from B to A. The two trains depart from A and B at the same time. When they meet, the slow train travels 90 kilometers less than the fast train. What is the distance in kilometers between A and B?
快车从甲地到乙地要10小时，慢车从乙地到甲地要15小时，两车同时从甲乙两地相对开出，相遇时慢车比快车少行90千米．甲乙两地间的距离是多少千米？
<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>1/30 = around 0.033333</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">(1/30) * 6</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">90 / (1/5)</gadget>
<output>450</output>

<result>450</result>