A person is on a railway bridge with A at one end and B at the other end. The distance between him and A is (3/8) of the length of the bridge. He hears a train coming towards A, the speed of the train is 80kph. If he runs towards A, he will meet the train at A. If he runs towards B, the train will overtake him at B. What is the speed of the man?
某人正在一座铁路桥上，桥的一端为A，另一端为B，他离A处的距离为桥长的(3/8)．他听到一列火车正向A处驶来，火车的速度是80kph．如果他跑向A，他将与火车在A处相遇，如果他跑向B，火车将在B处追上他，这人的速度是多少？
<gadget id="calculator">3 / 8</gadget>
<output>3/8 = around 0.375</output>

<gadget id="calculator">1 - (3/8) - (3/8)</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">80 * (1/4)</gadget>
<output>20</output>

<result>20</result>