What value of k makes the equation true? 12 (-17) = - 17 + k

Is there any sign between 12 and - 17 on the left side?

if no, then this is to be interpreted as a multiplication and is equal to - 204.

so we have - 204=-17+k

which means

-204+17=k

-187=k

so k is - 187

if thre is a plus between the 12 and (-17) then k would be 12 (and both sides of the equation would be essentially the same, just inverted order)