Which ratio is equal to 5/6 and
which ratio is not equal to 4/9?

It seems that you have missed the relevant options for your question, but hope these answers can help you find the one. Anyway, the ratio that can be equal to 5/6 is 10/12. Or it can be the following: 15/18, 20/24 or 25/30.
The ratio that is not equal to 4/9 among the given choices which are 45/95,   16/36,   8/18,   20/45 is 45/95. The answer is the first option. Since 45/95 is 9/19. Hope these answers help.