A and B start from two places 5000 meters apart and walk towards each other. A's speed is 70 m/min, B's speed is 30 m/min, and A's dog's speed is 150 m/min. The dog and A set off at the same time, and when it meets B, it returns to look for A, and when it meets A, it turns around to look for B. This goes back and forth until A and B meet each other. How many meters did the dog run in total?
甲、乙两人从相距5000米的两地出发，相向而行．甲的速度是70米/分，乙的速度是30米/分，甲带的一条狗的速度是150米/分．狗与甲同时出发，碰到乙就返回来找甲，碰到甲再掉头找乙．如此往返，直到甲、乙两人相遇为止．这条狗一共跑了多少米？
<gadget id="calculator">70 + 30</gadget>
<output>100</output>

<gadget id="calculator">5_000 / 100</gadget>
<output>50</output>

<gadget id="calculator">150 * 50</gadget>
<output>7_500</output>

<result>7_500</result>