Trumpeter a holds a b-flat note on the trumpet for a long time. person c is running towards the trumpeter at a constant velocity. person b is running away from the trumpeter at the same rate. person d is standing still the whole time.
which person hears a frequency that is lower than the b-flat?
a) person a
b) person b
c) person c
d) person d

The person running towards the trumpet, Mr. C,
hears a higher frequency.

The person running away from the trumpet, Mrs. B,
hears a lower frequency.

The trumpeter, Mr. A, and the person who is just standing still
and listening, Miss D, both hears the beautiful perfect B-flat.

By dividing you can find the answer

Neptune is the eighth planet from the sun. it was the first planet to get its existence predicted by  mathematical calculations  before it was actually seen through a telescope on sept. 23, 1846. irregularities in the orbit of  uranus  led french astronomer alexis bouvard to suggest that the gravitational pull from another celestial body might be responsible. german astronomer johann galle then relied on subsequent calculations to   spot neptune via telescope. previously, astronomer galileo galilei sketched the planet, but he mistook it for a star due to its slow motion. in accordance with all the other planets seen in the sky, this new world was given a name from greek and roman mythology — neptune, the roman god of the sea.