The average speed of the bus from Lansing to Detroit is

while the average speed of the bus from Detroit to Lansing is

The distance covered by the bus in the two trips is the same (the distance between the two cities), therefore, the average speed of the round trip can be calculated as the mean of the two speeds:
I'm pretty sure the answer would be D
Yes, even light rays can vary in wavelength and frequency, if the length of the ray is sorter, it becomes more energetic and has a higher frequency. If you're talking about a ray tracing diagram for lenses or mirrors, the length of the ray doesn't really matter unless you're finding the path length but there are some procedures for that too. Let me know if I missed what you were asking.
Answer:
1 mi = 5280 ft * 12 in/ft = 63360 in
A convenient conversion factor (to remember) is 1 m = 39.37 in
63360 in / (39.37 in / m) = 1609.3 m
26 mi + 285 m = 26 * 1609.3 + 385 = 42,228 m