A student solves 4 = x + 9 and reports: add 9 to both sides → 13 = x + 9, therefore x = 13. Critique the student's steps and choose the accurate correction.

Incorrect method. The proper step is subtract 9 from both sides: 4 − 9 = x, so x = −5 (solution set {−5}).

The student should have divided both sides by 9 to isolate the variable, producing x ≈ 0.444 which is the appropriate approach when dealing with linear constants.

Partially correct; instead one should multiply both sides by −1 then add 9 to isolate x giving x = 5 as the solution.

Correct method; adding 9 to both sides yields 13 = x + 9 and therefore x = 13 is the valid solution after cancelling, so no correction needed.