I assume you mean (1/12)(k+4) and not

1/[12(k+4)]

The way you wrote it, it could be either one. They are NOT the same.

The same thing goes for your "1/3k". Do you mean (1/3)k = k/3? or 1/(3k) ?

Your k+1/4 is also ambiguous. Do you mean (k+1)/4? or k + (1/4) ?

Just do the multiplying and combine "like" terms (k-terms and constants) separately. The (if you wish) you can solve for k. You need to attempt this yourself if you want to learn the subject and graduate.

I assume that you know the rule that a minus sign outside parentheses changes the sign of everything inside.