Two people, A and B, start from A and B respectively and walk towards each other. After arriving at the destination, they immediately turn around and return to the starting point. The first time they met, they were 800 meters away from A, and the second time they met, they were 500 meters away from B. How many meters away are the grounds?
甲乙二人分别从A、B两地出发相向而行，到达目的地后马上掉头回到出发地，他们第一次相遇距A地800米，第二次距B地500米，A、B两地相距多少米？
<gadget id="calculator">800 * 3</gadget>
<output>2_400</output>

<gadget id="calculator">2_400 - 500</gadget>
<output>1_900</output>

<result>1_900</result>