Question

I need help! Thanks!

Answer 1

If you have to negative... as in... (-9-9) do you add or subtract?

Answer 2

add the opposite

Answer 3

$$-9-9=-9+(-9)$$

Answer 4

Definition of subtraction
For all real numbers a and b,
The difference a-b is defined by
$$a-b=a+(-b)$$
To subtract b, add the opposite of b.