Two people, A and B, travel from A to B. A’s speed is 20 kilometers per hour, and B’s speed is 25 kilometers per hour. Half an hour after A’s departure, B starts off. As a result, both of them arrive at B at the same time. What is the distance between A and B?
甲、乙两人从A地到B地，甲的速度是每小时20千米，乙的速度是每小时25千米，甲出发半小时后，乙才出发，结果两人同时到达B地，问A、B两地的距离是多少．
<gadget id="calculator">25 - 20</gadget>
<output>5</output>

<gadget id="calculator">0.5 / 5</gadget>
<output>0.1</output>

<gadget id="calculator">20 * 0.1</gadget>
<output>2</output>

<gadget id="calculator">25 * 2</gadget>
<output>50</output>

<result>50</result>