To build a road, A can finish it in 12 days alone, and B can finish it in 18 days alone. If the two teams work together, how many days will they finish it?
修一条路，甲独做12天修完，乙独做18天修完，如果两队合作，多少天修完．
<gadget id="calculator">1 / 12</gadget>
<output>1/12 = around 0.083333</output>

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

<gadget id="calculator">(1/12) + (1/18)</gadget>
<output>5/36 = around 0.138889</output>

<gadget id="calculator">1 / (5/36)</gadget>
<output>36/5 = around 7.2</output>

<result>36/5 = around 7.2</result>