I need help with a magic square, been stuck on it for 3 days

Question

The question is " use the numbers -12, -9, -6, -3, 0, 3, 6, 9, and 12 to form a magic square. And explain the process and reasoning. 

Answer 1

First you need to figure out what each column/row is equal to.  Add all the number and divide by 3 = 0

 

Then set up your square

 

-12    0    12

  9    -6    -3

  3     6    -9