The price of an article is first increased by 20% and later on decreased by 25% due to reduction in sales. Find the net percentage change in final price of the article.

### Concept & Formula When a value undergoes successive percentage changes $x$ and $y$, the net percentage change is given by the formula: $$Net \% Change = x + y + \frac{xy}{100}$$ (Increases are positive, decreases are negative). ### Step-by-Step Solution 1. Identify the changes: First change ($x$) = $+20\%$ (increase) Second change ($y$) = $-25\%$ (decrease) 2. Apply the successive percentage formula: $$Net Change = 20 + (-25) + \frac{20 \times (-25)}{100}$$ $$Net Change = -5 + \frac{-500}{100}$$ $$Net Change = -5 - 5 = -10\%$$ 3. Interpret the result: A net change of $-10\%$ means a $10\%$ decrease. Since $10\%$ decrease is not among the options (20%, 18%, 38%), the correct choice is "None of these". ### Exam Strategy & Shortcut Assume the initial price is 100. After $20\%$ increase: $100 \rightarrow 120$. After $25\%$ decrease (which is $1/4$th): $120 \rightarrow 120 - 30 = 90$. Net change = $100 \rightarrow 90$, which is a $10\%$ decrease. ### Common Pitfall Simply adding the percentages together ($+20\% - 25\% = -5\%$), which ignores the compounding effect of the successive changes. ### Final Answer Therefore, the correct answer is **None of these**.