If a batch of parts is processed by the master alone, it will take 12 hours to complete. If it is processed by the apprentice alone, it will take 18 hours to complete. Now the master will process it alone for 5 hours, and the rest will be processed by the apprentice alone. How many hours will it take to complete?
一批零件，如果由师傅单独加工，要12小时完成．如果由徒弟单独加工，要用18小时才能完成．现在由师傅先单独加工5小时，余下的再由徒弟单独加工，还要多少小时可以完成？
<gadget id="calculator">1 / 12</gadget>
<output>1/12 = around 0.083333</output>

<gadget id="calculator">(1/12) * 5</gadget>
<output>5/12 = around 0.416667</output>

<gadget id="calculator">1 - (5/12)</gadget>
<output>7/12 = around 0.583333</output>

<gadget id="calculator">1 / 18</gadget>
<output>1/18 = around 0.055556</output>

<gadget id="calculator">(7/12) / (1/18)</gadget>
<output>21/2 = around 10.5</output>

<result>21/2 = around 10.5</result>