The real point of the problem is to test your ability to read definitions- the problem defines "expectal", it is not a standard mathematics term.
"Let the expectal(x) be defined for all x as the smallest prime number that is greater than x/2"
To find the "expectal" of x, find "x/2", that is divide x by 2, then determine the smallest prime number larger than that.
That is exactly what was said in the thread you link to!
For example to find expectal(7), divide 7 by 2 to get 7/2= 3.5. A prime must be an integer so check integers- 4 is larger than 3.5 but is not a prime. 5 is larger than 3.5 and is a prime. It is the smallest prime larger than 7/2: expectal(7)= 5.
expectal(14)= 11 because 14/2= 7. 7 itself is a prime but is not "larger than 7". 8, 9, and 10 are not primes but 11 is. 11 is the smallest prime larger than 14/2= 7.
As I said initially, the point of this problem is to test your ability to understand that definition- basically to test your ability to follow directions!