Find the student’s error in solving the following inequality.
2 < –3x –4 < 5
6 < –3x < 5
–2 > x > –5/3

a. the student should have added 4 to all parts (left, middle, and right) to get 6 < –3x < 9.

b. the student divided 6/–3 incorrectly.

c. the student should not have switched the direction of the sign in the final step.