Wee see rainbows due to the geometries of the raindrops. when the sun shines behind, rays of light enter the raindrops and this light are refracted. The lights are then reflected from the back of the raindrop and refracted again as it passes the rain drop. Refraction in this sense is the cause for splitting the light into several colors.
Answer:
20 m/s westward
Explanation:
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

and the direction will be westward (negative sign).
6.35x10^-4 OR 6.3x10-4 (if only one decimal number is allowed)