A and B are traveling together on foot. One hour after A starts, B starts from the same place in the same direction and walks for two hours to reach the place A visited 45 minutes ago. Afterwards, B accelerates 500 meters per hour and takes three hours. After chasing A, ask A's speed.
甲、乙两人步行远足旅游，甲出发后1小时，乙从同地同向出发，步行两小时到达甲于45分钟前曾到过的地方，以后乙加速每小时500米，用了三小时追到了甲，问甲的速度．
<gadget id="calculator">500 * 3</gadget>
<output>1_500</output>

<gadget id="calculator">9 / 17</gadget>
<output>9/17 = around 0.529412</output>

<gadget id="calculator">8 / 17</gadget>
<output>8/17 = around 0.470588</output>

<gadget id="calculator">(9/17) - (8/17)</gadget>
<output>1/17 = around 0.058824</output>

<gadget id="calculator">1_500 / (1/17)</gadget>
<output>25_500</output>

<gadget id="calculator">25_500 * (8/17)</gadget>
<output>12_000</output>

<result>12_000</result>