1. **State the problem:** Find the percent difference between 0.012 and -0.009. 2. **Formula:** Percent difference between two values $a$ and $b$ is given by: $$\text{Percent Difference} = \frac{|a - b|}{\frac{|a| + |b|}{2}} \times 100$$ 3. **Apply values:** Here, $a = 0.012$ and $b = -0.009$. 4. Calculate the numerator (absolute difference): $$|0.012 - (-0.009)| = |0.012 + 0.009| = 0.021$$ 5. Calculate the denominator (average of absolute values): $$\frac{|0.012| + |-0.009|}{2} = \frac{0.012 + 0.009}{2} = \frac{0.021}{2} = 0.0105$$ 6. Calculate the percent difference: $$\frac{0.021}{0.0105} \times 100 = 2 \times 100 = 200\%$$ 7. **Answer:** The percent difference between 0.012 and -0.009 is **200%**.