Students in Class A and Class B set off from the school at the same time to Ocean Park, which is 54 kilometers away from the school. There is only one car in the school, and its speed is 45 km/h. This car can take exactly one class of students. In order to let the students of the two classes reach the park at the same time as soon as possible, the students in class A walk first, and the students in class B Take the car first, when the car arrives at a certain place, the students in class B get off the car and continue walking, and the car returns to pick up the walking students in class A. If the walking speed of the two classes is 5 km/h, how many hours will it take for the students of the two classes to reach the park at the same time in the shortest time? (The time taken to get on and off the bus is not counted)
甲、乙两个班的学生同时从学校出发去距学校54千米的海洋公园．学校只有1辆汽车，它的速度是45千米/时，这辆汽车恰好能坐1个班的学生，为了让两个班的学生尽快同时到达公园，采取甲班学生先步行，乙班学生先乘车，汽车到达中途某地点时，乙班学生下车继续步行，汽车返回接甲班步行的学生．如果两个班学生步行速度都是5千米/时，那么两个班的学生用最短的时间同时到达公园用多少小时？(上、下车所用时间不计)
<gadget id="calculator">1 + 4</gadget>
<output>5</output>

<gadget id="calculator">1 + 4 + 1</gadget>
<output>6</output>

<gadget id="calculator">5 / 6</gadget>
<output>5/6 = around 0.833333</output>

<gadget id="calculator">54 * (5/6)</gadget>
<output>45</output>

<gadget id="calculator">45 / 45</gadget>
<output>1</output>

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

<gadget id="calculator">(1/6) / 5</gadget>
<output>1/30 = around 0.033333</output>

<gadget id="calculator">54 * (1/30)</gadget>
<output>9/5 = around 1.8</output>

<gadget id="calculator">1 + (9/5)</gadget>
<output>14/5 = around 2.8</output>

<result>14/5 = around 2.8</result>