Please asap I need this for a test

3

Step-by-step explanation:

(f O g) this basically means that the input x first goes trough the function g and then f. Like f(g(x)).

So when x went trough g, you got the output g(x) and then this went trough f and you got f(g(x)) = -8 = 'f(x)'.

With this in mind you can retrace your steps by first looking at what input can get -8 as an output, for f this is -4. this means g(x) = -4

Then you look at what input (this is the x you're looking for) gets you the ouput -4. Looking at the second image you'll picture see that it's the input 3.