Answer:
or 
Explanation:
Number of longitudes on Earth = 
In one hour the Earth rotates 
So, 
takes 
Since the longitude is in the East the time difference will be added.
So, if it is noon in Greenwich the time at 100 degree East will be 
or .
Any practices should best be based on a research - this is the correct answer. (a. child development and research) Research is the best source of actual knowledge, rather than people's best guesses (people's best guesses might lead government regulations, but it would be better if they also followed research results.).
They did this so when the Mongols took over China, the Chinese could not gain high power and over throw the mongols.
The Federal government would be too weak to do enforce its laws
Over a life time of an individual intelligence tends to increase. You learn more things that will have more value then the things you learned earlier in life.
