The Goal

Simplify:

The Mistake

(Roll the mouse over the algebra to see a hint in red)

The Correction

(Roll the mouse over the area above to see the correction in blue)

An Explanation

Use care with fractions. A good strategy is to write down intermediate steps, which makes you take the time needed to compute correctly.
(It is possible that the student mistakenly multiplied the fraction by -1 instead of performing a subtraction.)

Visit Algebra Facts > Adding and subtracting fractions to learn more.