For a manuscript, the time required for A, B, and C to play alone is 10 hours, 12 hours, and 15 hours respectively. Now the three are fighting together, but A withdraws early due to another task in the middle, and it takes 6 hours to complete the task. A only played for a few hours?
一份稿件，甲、乙、丙三人独打需要的时间分别是10小时、12小时、15小时．现在三人合打，但甲因中途另有任务提前撤出，结果用6小时完成任务．甲只打了几小时？
<gadget id="calculator">1 / 12</gadget>
<output>1/12 = around 0.083333</output>

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

<gadget id="calculator">(1/12) + (1/15)</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">(3/20) * 6</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">1 - (9/10)</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">(1/10) / (1/10)</gadget>
<output>1</output>

<result>1</result>