If 3f+ 1 < 2f < 9 - f, which of the following must be true?
I. -1 < f < 3
II. f < -1
III. f < 3  Select.
A) II only  B) III only  C) I and II only  D) II and III only  E) I, II and III
Just try plugging f in a number like 0 or 1, and you'll quickly find that the inequality doesn't hold.   So you can immediately cross out any answers with I or III, leaving just (II only) II only.
<result>A</result>
If 3f+ 1 < 2f < 9 - f, which of the following must be true?
I. -1 < f < 3
II. f < -1
III. f < 3