Shortcut TrickFractional equivalent of 25% increase = +1/4 To keep the expenditure constant, the consumption must be reduced by the ratio: −1 ÷ (4 + 1) = −1/5 Percentage reduction = (1/5) × 100% = 20% ∴ The correct answer is 20%. Alternate Method Given: Increase in the price of sugar = 25% Formula Used: Expenditure = Price × Consumption Reduction % = [R ÷ (100 + R)] × 100% (where R is the percentage increase) Calculations: ⇒ Let initial price = 100 units and initial consumption = 100 units. ⇒ Initial expenditure = 100 × 100 = 10000 units. ⇒ New price after 25% increase = 100 + 25 = 125 units. ⇒ Let the new consumption be C. ⇒ To keep expenditure constant: 125 × C = 10000 ⇒ C = 10000 ÷ 125 = 80 units. ⇒ Decrease in consumption = 100 − 80 = 20 units. ⇒ Percentage reduction = (20 ÷ 100) × 100% = 20%. ∴ The correct answer is 20%. Related Concepts: Price and Consumption Rule When Expenditure is constant, Price and Consumption are inversely proportional. An increase in price leads to a proportional decrease in consumption. Percentage Increase / Decrease Concept If value A is R% more than B, then B is less than A by exactly [R ÷ (100 + R)] × 100%. Standard Fractional Equivalents 1/2 = 50%, 1/3 = 33.33%, 1/4 = 25%, 1/5 = 20%, 1/6 ≈ 16.66%.