ANSWER:
STEP:
Add -k and 8k. If you don't know why, since there is two "-". Two of those sign mean to add. And negative plus a positive is negative or positive. Or, you can just do 8k-1k. That is the same. You'll get 7k.
-k-(-8k)
= -k + 8k (two negatives equal one positive)
= 8k-k (flip it around because of the commutative property)
=7k (basic subtraction)
I really hope that helped :)
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