how to complete a addition matrix for 3rd grade level?

Question

the matrix has 7 squares going across and 7 going down.
the top line going across reads +/- 3 5 1 2 4 8 and the first column going down reads +/- 7 6 0 5 7 2.
there is a second matrix with the same number of boxes but there are numbers filled in through out.

Answer 1

This is just a guess. You call this an addition matrix; I don't understand what the "+/-" symbol in the upper left square would mean. But here is what I think you do to fill in the matrix:

For each blank square, look at the number at the top of the column that it's in, and look at the number in the first (that is, leftmost) square of the row that it's in, add those two numbers, and put the result in the empty square. For example, for the empty square in the second row and second column (just under the "3" and just to the right of the "7"): I would put 10 in that square. In the next square to its right (just under "5"), I would put 12. In the square just under this one, I would put 11.
And so on.

Sorry, no idea what the second matrix is for. Maybe it's a filled-in example?