A and B start from A and B at the same time and walk towards each other. When they meet, A has already walked 1000 meters; if A doubles the speed from the beginning, when they meet, A has already walked 1200 meters. What is the distance between A and B?
甲乙两人分别从A、B两地同时出发相向而行，相遇时甲已经走了1000米；如果甲一开始就把速度提高为原来的两倍，相遇时，甲已经走了1200米．A、B两地相距多少米？
<gadget id="calculator">1_000 / 2</gadget>
<output>500</output>

<gadget id="calculator">1_000 + 500</gadget>
<output>1_500</output>

<result>1_500</result>