## Elementary Algebra

$-15$
RECALL: $a-b=a+(-b)$ Thus, $-6-9=-6+(-9)$ The numbers being added have the same sign. Perform the following steps: (1) Add their absolute values. $|-6| + |-9| = 6+9 = 15$ (2) The sum will have the same sign as the original numbers. Thus, $(-6)+(-9) = -15$