It takes 10 hours for the fast train to go from A to B, and 15 hours for the slow train to go from B to A. The two cars are traveling towards each other from A and B at the same time. After how many hours, the two cars will meet.
快车从甲地到乙地要行10小时，慢车从乙地到甲地要行15小时，两车同时从甲乙两地相向而行，多少小时后两车相遇．
<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>

<result>6</result>