A manuscript can be completed by two typists A and B in 12 hours. Now they are working together. Because A is absent from work for 5 hours in the middle, it takes 15 hours to complete it. If A alone typed it, how many hours will it be completed? ?
一份稿件，甲、乙两个打字员合打12小时可以完成，现在两人合打，由于中途甲因故旷工5小时，因此用了15小时才完成，如果由甲单独打，多少小时完成？
<gadget id="calculator">1 / 12</gadget>
<output>1/12 = around 0.083333</output>

<gadget id="calculator">15 - 5</gadget>
<output>10</output>

<gadget id="calculator">(1/12) * 10</gadget>
<output>5/6 = around 0.833333</output>

<gadget id="calculator">1 - (5/6)</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">(1/6) / 5</gadget>
<output>1/30 = around 0.033333</output>

<gadget id="calculator">(1/12) - (1/30)</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">1 / (1/20)</gadget>
<output>20</output>

<result>20</result>