Answer: 
Explanation:
Given
Distance between two speakers is 8 m
Man is standing 12 away from the wall
When the person moves 3 parallel to the wall
the parallel distances from the speaker become 4+3, 4-3
Now, the difference of distances from the speaker is

Condition for destructive interference is

for second destructive interference; n=2

Disaster. (like my life) It'll affect the animals and there will be no way to get their food without water.Hope this helped :)
Electromagnetic waves differ from mechanical waves in that they do not require a medium to propagate . this means that electromagnetic waves can travel not only through air and solid materials bit also through vacuum of space.