There are 90 tons of cargo, and it takes 10 hours for vehicle A to transport it alone, and 18 hours for vehicle B to transport it alone. If the two vehicles are transported at the same time, how many hours can they be transported? What is the correct column
有90吨货物，甲车独运10小时运完，乙车独运18小时可以运完，两车同时运，几小时可以运完？正确列式是多少
<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

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

<gadget id="calculator">(1/10) + (1/18)</gadget>
<output>7/45 = around 0.155556</output>

<gadget id="calculator">1 / (7/45)</gadget>
<output>45/7 = around 6.428571</output>

<result>45/7 = around 6.428571</result>