To enter a manuscript, A can complete the entry in 4 hours alone, and B can enter (1/6) of this manuscript every hour. How many hours did the two work together?
录入一份稿件，甲单独录入4小时完成，乙每小时可录入这份文稿的(1/6)．两人合作几小时完成？
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 / 6</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">(1/4) + (1/6)</gadget>
<output>5/12 = around 0.416667</output>

<gadget id="calculator">1 / (5/12)</gadget>
<output>12/5 = around 2.4</output>

<result>12/5 = around 2.4</result>