As you can see in this picture we have a point on y- axis which is our y-intercept and f(x)
so first we should find what WAS the y-intercept before adding k
so we can say:
f(x) = 2(0) - 3 = -3
so it WAS -3 .... but in this picture is -7
so you have:
-3 + k = -7
k = -7 + 3 = -4
so k is equal to -4 :)))
i hope this is helpful
have a nice day