A. 60 miles
B. 5 hours
Unless you are looking for slope, in which case the answer is different
The answer is "B" - If there are no windows then there will be no light coming in, and therefore you don't have to worry about what time of day you do the experiment at.
Explanation:
Given that,
Bill is riding his bicycle at 5 m/s eastward: and Carlos is driving his car at 15 m/s westward.
Taking eastward as positive direction, we have:
is the velocity of Bill with respect to Amy (which is stationary)
is the velocity of Carlos with respect to Amy.
Bill is moving 5 m/s eastward compared to Amy at rest, so the velocity of Bill's reference frame is

Therefore, Carlos velocity in Bill's reference frame will be

So, the magnitude is 20 m/s and the direction is westward (negative sign).
Explanation:
Displacement is the straight line distance from the starting position to the final position.
Person X walks halfway around circle. So her displacement is 100 m.
Person Y walks 3/4 of the way around. So his displacement is 50√2 m ≈ 70.7 m.
Person Z walks completely around the circle, so their displacement is 0 m.
Therefore:
Z < Y < X