A large truck and a small car go from A to B at the same time. The car returns immediately after arriving at B, but the speed increases (1/2). The two vehicles meet for the first time after 2 hours. At point B, the car just arrived at the midpoint of the two places. How much time does it take for a car to go back and forth from point A to point B?
一辆大货车和一辆小轿车同时从甲地到乙地，小轿车到达乙地后立即返回，但速度提高(1/2)两车经2小时第一次相遇，相遇后当大货车到达乙地时，小轿车正好到达两地的中点．小轿车甲地到乙地间往返一次共需多少时间？
<gadget id="calculator">2 + 1</gadget>
<output>3</output>

<result>3</result>