There are a total of 100 trees. The first shift needs 6 hours to plant alone, and the second shift needs 8 hours to plant alone. Now, how many hours will it take to plant the two shifts together?
一共有100棵树，一班单独种，需要6小时，二班单独种，需要8小时，现在两班合种，需要多少小时．
<gadget id="calculator">1 / 6</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">1 / 8</gadget>
<output>1/8 = around 0.125</output>

<gadget id="calculator">(1/6) + (1/8)</gadget>
<output>7/24 = around 0.291667</output>

<gadget id="calculator">1 / (7/24)</gadget>
<output>24/7 = around 3.428571</output>

<result>24/7 = around 3.428571</result>