Which function represents a reflection of ƒ (x) = 2x?

Let f (x) = 2x + 2

You'll see it is a straight line, slope 2 (which is positive, i. e. going uphill as we go left to right) and y-intercept 2.

Now let's consider - f (x).

This gives us

-f (x) = - 2x - 2