To build a 3 km long road, it will take 10 days for the repair team A alone, and 8 days for the B team. If the two teams practice together at the same time, how many days can they finish? What is the correct column
修一条3千米长的公路，单独修甲队要10天修完，乙队要8天修完．如果两队同时合修，几天能修完？列式正确的是多少
<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

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

<gadget id="calculator">(1/10) + (1/8)</gadget>
<output>9/40 = around 0.225</output>

<gadget id="calculator">1 / (9/40)</gadget>
<output>40/9 = around 4.444444</output>

<result>40/9 = around 4.444444</result>