Since both numbers in all the equations are negative add them together like positive numbers, but put a negative number in front of it
-2 + -6 = -8
-4 + -9 = -13
-8 + -0 = -8
^^^Technically 0 is neither negative nor positive
Hope this helped!
-2 +- 6 is -8 or 4
-4 +- 9 is -13 or 5
-8 +- 0 is -8 (Since 0 is the 0 whether it is positive or negative)
