If the 2 given points are endpoints, then we're in business. The formula for the midpoint is

. If the endpoints of our segment are the coordinates (1,2) and (12,14), our formula would be filled in as follows:

which simplifies to (13/2, 8). See? It's pretty simple once you know how to do it.
It will translate 5 to the left.
28.3 / 9 = 3.14444444......
3.14 round to 3
No.
So, there are 1000 milligrams in one gram, making the 4000 mgs equal to 4 grams.
There are 1000 grams in one kilogram, so 4 kilograms is equal to 4000 grams.
4000 =/= 4
So, 4 kilograms and 4000 milligrams are not equal.