Student: If x, y, and z are positive integers such that x is a factor of y and y is a factor of z, which of the following is NOT necessarily an integer?
Options:
(A) (x + y) /z
(B) (y + z) /x
(C) yz/x
(D) (2y + 3z) /x
(E) (xy + z) /y.
Another student: Let's say, hmmm...
As per the question, let x = 2, y = 6, and z = 12. Plugging these into the answer choices, only A does not yield an integer. Final answer: (A).