Using De Morgan's laws to find which expression equals X

[omni]

is known that A and B are events.
now i asked to decide form the options A-D which one can have the X value.

so i tried to use the De Morgan's laws but i am not sure if this is the correct way.
so i need help here.

thanks.

 

[Mark44]

is known that A and B are events.
now i asked to decide form the options A-D which one can have the X value.

so i tried to use the De Morgan's laws but i am not sure if this is the correct way.
so i need help here.

No, it's not. What you need to do is to eliminate that three answers that aren't possible.

You're given P(A) = .5 and P(B) = .8. The four answers are A) 0, B) .4, C) .8, and D) 1.

 

[omni]

ok i got the answer B=0.4

do i correct?

 

[Mark44]

That's the one I get.

 

[omni]

thank you very much for helping.