The function f (x) = 1/2x-6 was replaced with f (x+k) = 1/2x-4. what is the value of k

Given that the function f (x) = 1/2x-6 was replaced with f (x+k) = 1/2x-4, then the value of k we be as follows:

f (x) = 1/2x-6

replacing x1=x+k

f (x+k) = 1/2 (x+k) - 6

equating the above to 1/2x-4 we shall have:

1/2 (x+k) - 6=1/2x-4

simplifying we obtain:

1/2x+1/2k=1/2x-4

1/2k=-4

hence

k=-8