Answer:
all the details are in the attached picture, the answers are marked with colour.
Answer:
Constructive interference
Explanation:
Here, the medium is same, same wavelength, same frequency, same amplitude and same direction of propagation.
Let the intensity of waves be I which is same for both
The formula for the net intensity is

where, Ф be the phase difference
So, 
Here, IR is maximum so the interference is constructive in nature.
The answer is d hope this helps
Let point A be 0.0 miles (first city)
Let point B be 160.5 miles (first city to second city)
Let point C be 28.5 miles (first city to mail stop)
Take C – A = C [28.5 - 0.0 = 28.5] (This checks the distance between city 1 and Mail stop)
Then Take B – C = Distance from the first city to the second city [160.5 - 28.5 = 132 Miles]
Answer: The Mail stop is 132 miles from the Second City.