Each of the spaces in a three-by-three grid has one of the integers from one to nine. Each value is used once.
1) The three values in the top row sum to 15, and none are prime.
2) The three values in the middle row are all odd.
3) The three values in the bottom row sum to 15.
4) The three values in the middle column are 7, 8, and 9, in some order.
5) The three values in the right column sum to 6.
How are the integers arranged in the grid?
Submit your answer to Gene Wirchenko <email@example.com>. Your answer should be in the form of a proof. That means to show how your answer must be correct. The deadline is Wednesday, April 1, 2015 at noon Pacific Time. I will post the answer shortly after.