Answer:
-17
Step-by-step explanation:
(I originally posted this as a comment because Brainly was not allowing me to answer).
-8 is a negative number, which means many operations don't work the same on it. Subtracting a positive number from a negative number will give you the same result as adding the two positive numbers (in this case, 8 + 9), though the answer will also be negative. Hope this helps!