Need , not really understanding this : )

d. y-3 = f(x)

Step-by-step explanation:

we don't know what f(x) is. but we can see that the red line is 3 units above the black line. so we are adding 3 to whatever f(x) is. so the red line should have the equation

y = f(x) +3

subtract 3 from both sides

y-3 = f(x)

answer is x<