Greatest possible integer value of x+y? I found a interesting question in one exam.
If 5 <  x < 10 and y = x + 5, what is the greatest possible integer value of x + y ?
(A) 18
(B) 20
(C) 23
(D) 24
(E) 25

MySol:  For max value of x+y , x should be 9.
 So x+y =  9+14 = 23
But this is not correct. 
Can someone explain.

Note that $x+y=2x+5$. The greatest possible integer value of $2x$ occurs at $x=9.5$.
Remark: Unfortunately, a bit of a trick question. Not nice! One of my many objections to multiple choice questions is that they are too often designed to fool people into giving the "wrong" answer. 
