and B work together to process a batch of parts, which takes 10 hours to complete. After working together for 4 hours, A left for some reason, and B did it alone, and it took another 18 hours to complete all the tasks. If this batch of parts is made by B alone, how many hours will it take to complete the processing?
甲、乙两人共同加工一批零件，需要10小时完工．在共同工作4小时后，甲因故离开，由乙独做，又用了18小时完成了全部任务．如果这批零件由乙独做，需要几小时加工完成？
<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">(1/10) * 4</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (2/5)</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">(3/5) / 18</gadget>
<output>1/30 = around 0.033333</output>

<gadget id="calculator">1 / (1/30)</gadget>
<output>30</output>

<result>30</result>