Answer:

it is -15. (D.)

Step-by-step explanation:

-6 and -9 have the same integer and that is negative (-) thus we will add both numbers.

Answer:

-15

Step-by-step explanation:

• (+)+(+)=(+)

• (-)+(-)=(-)

• (+)+(-)= subtract the numbers and put the sign of the larger number

• (-)+(+)= subtract the numbers and put the sign of the larger number

• (-)+(-)=(-)

• (-6)+(-9)=(-15)