How do you find the missing number?

Question

4/5 > 2/x

Answer 1

If x>0,

4x > 5*2
x > 5/2

If x<0,
4x < 5*2
x < 5/2
But x<0, so x < 0 < 5/2 is a solution.
Naturally, since if x<0, 2/x < 0, so 4/5 > 2/x for any negative x.