Wang Jun heard twice, and the total length of the two transmissions remained unchanged.

So suppose it took x seconds to hear the noise for the first time and x+2 seconds to hear it for the second time.

According to distance = time * speed, x*5000=(x+2)*340 is obtained.

5000x=340x+680？ The solution is x≈0. 1459.

Total distance =5000*0. 1459=729 meters ~

Thanks for adoption