How many thumbs down votes did the video get

So this is what you know
18 thumbs up
Ratio of 9 thumbs up: 2 thumbs down

So for every 9 thumbs up, you get 2 thumbs down.

You know you have 18 thumbs up.

9 thumbs up * 2 = 18 thumbs up

So you know then that for every 18 thumbs up, you get 4 thumbs down (2 thumbs down *2h).

So you’ll have a ratio of 18:4 (for every 18 thumbs up you have 4 thumbs down).

Since the video only got 18 thumbs up, you now know that you have 4 thumbs down by looking at your new ration of 18:4.

So you have 4 thumbs up.

Does that help?
-lucystudies