Answer:
k=-20
Explanation:
We move all terms to the left:
k-2k+3k-4k+5k-6k+7k-8k+9k-10k-(100)=0
We add all the numbers together, and all the variables
-5k-100=0
We move all terms containing k to the left, all other terms to the right
-5k=100
k=100/-5
k=-20