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)