The function f(x) = 2x -3 is changed to f(x)+k. the new function f(x) can be represented by the graph below. what is the value of k?

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 

Number nine is f(x)= 40x : ) hoped i ya