job is completed in 5 hours (1/4), and B is completed in 4 hours (1/6). A will do 5 hours first, and then how many hours will it take for the two to cooperate?
一件工作，甲5小时完成了(1/4)，乙4小时完成了(1/6)，甲先做5小时，接着两人合作还需几小时？
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 - (1/4)</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">(1/4) / 5</gadget>
<output>1/20 = around 0.05</output>

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

<gadget id="calculator">(1/6) / 4</gadget>
<output>1/24 = around 0.041667</output>

<gadget id="calculator">(1/20) + (1/24)</gadget>
<output>11/120 = around 0.091667</output>

<gadget id="calculator">(3/4) / (11/120)</gadget>
<output>90/11 = around 8.181818</output>

<result>90/11 = around 8.181818</result>