If 3a + 1 < 2a < 9 - a, which of the following must be true?
I. -1 < a < 3
II. a < -1
III. a < 3
Options.
A) II only B) III only C) I and II only D) II and III only E) I, II and III
Just try plugging a 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 3a + 1 < 2a < 9 - a, which of the following must be true?
I. -1 < a < 3
II. a < -1
III. a < 3