Teachers plz "Need help " echo

[bahaa_as]

time of the first echo = 2 seconds
time of the second echo = 2+ 2 = 4 seconds
the distance of the man from the first (nearer) mountain = v*t/ 2 = (340 *2)/2 = 340 m
the distance of the man from the second mountain = (340 * 4) /2 = 680 m
The distance between the two mountains = 340 + 680 = 1020 m = 1.020 Km