Hello!
[tex]6k - 1 + 6k\\[/tex]
Explanation:
↓↓↓↓↓↓↓↓↓↓↓↓
First this problem it should be the group like terms.
[tex]6k+6k-1[/tex]
Then you add similar by the elements.
[tex]6k+6k=12k[/tex]
[tex]=12k-1[/tex]
Answer⇒⇒⇒⇒⇒⇒⇒=12k-1
Hope this helps!
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-Charlie