40
-40 + 12 = -28
17 + 13 + 12 + 12 + 6 + 9 = 69.
12+8+10+12+11+9 = 62
15 +26+9+12
12 plus 9 equals 21.
40
28 + 12 = 40
12 minus 63 plus 9 is -42
-5x + x + 9 = -4x + 12 -4x + 9 = -4x + 12 9 = 12 This equation has no solution.
3 + 6 + 9 + 12 = 30
It is the associative property for the addition of numbers.