Answer:
k = 4
The graph of f(x) is y = x, ignoring the equation. Through translation we can solve this problem. Notice that the graph has shifted 4 units up or left.
Translations:
 = h units left
 = h units left
 = h units right
 = h units right
Hence the equation will be 
 . Here value of k is 4.
. Here value of k is 4.