It takes 10 hours for the express train to travel from Station A to Station B, and 15 hours for the slow train to travel from Station B to Station A. The two trains leave opposite to each other at the same time. When they meet, how much of the journey will the express train be away from Station B?
快车从甲站开往乙站要10小时，慢车从乙站开往甲站要15小时，两车同时从两站相对开出，相遇时，快车离乙站还有全程的几分之几？
<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">6 * (1/15)</gadget>
<output>2/5 = around 0.4</output>

<result>2/5 = around 0.4</result>