Question

use the number line above to solve: $-9 - (-9)$
a -18
b 18
c -1
d 0

Explanation:

Step1: Rewrite subtraction of negative

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

Step2: Simplify the expression

$-9 + 9 = 0$

Step3: Verify on number line

Start at $-9$, move 9 units right to reach $0$.

Answer:

D. 0