A boy stands between two vertical wall and fires a rifle. Under what condition will he hear a single echo from both walls? Calculate the distance between the walls if the single echo is heard six seconds later

Answer 1

when he stands between the walls at a point equidistance from them

Answer 2

when he stands between the walls at a point equidistant from them.
x=vt
330*6=1980

Answer 3

Where you stand at a point equidistant