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20+5k+5k=10k+20
We move all terms to the left:
20+5k+5k-(10k+20)=0
We add all the numbers together, and all the variables
10k-(10k+20)+20=0
We get rid of parentheses
10k-10k-20+20=0
We add all the numbers together, and all the variables
=0
k=0/1
k=0