Question 1208679
<pre>
F = { { Ø }, (x + y), 1/4, 1/3, 1/2, A, B, C, D }

Yes, the 9 elements of F are 

1. { Ø }
2. (x + y)
3. 1/4
4. 1/3 
5. 1/2 
6. A
7. B 
8. C 
9. D 

So you are right, the cardinality (count) is 9.
Comment:
The set { Ø } is not empty because it contains one element, the empty set Ø.
And Ø is only an element of { Ø } and not an element of F.  
The element (x + y) is a single number depending upon what number x and y are.

Edwin</pre>