-12(k+4)=60
−12×(k+4)=60
−12k−48=60 [ +48
−12k=12 [ /−12
k=−1 !
I found a slight error in your answer.
When you added 48, It should be 108 instead of 12.
So the answer should be k=-9 instead of k=-1.
+5265 
