SP = 5000 + 20% of 5000 = 5000 + 1000 = 6000.

To find the net percentage change, we track how a number changes through two successive percentage operations using the compound percentage formula.

Step 1: Apply the 25% increase

Let the original number be \(x\).

After increasing by 25%:

Step 2: Apply the 20% decrease

Now decrease this new value by 20%:

Step 3: Calculate the final value

Step 4: Find the net percentage change

Answer: The net percentage change is \(0\%\) (Option A)

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Assume the original number is 100.

After a 25% increase:

100×1.25=125

After a 20% decrease:

125×0.80=100

Final value =100, which is the same as the original value.

Therefore, the net percentage change is:

0%

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Key insight: When we increase by 25%, we multiply by 1.25. When we decrease by 20%, we multiply by 0.80. Since \(1.25 \times 0.80 = 1.00\), the number returns to its original value.

Boys:Girls = 3:2. If boys = 45, then 3x = 45, x = 15. Girls = 2x = 30

SP = CP + Profit = 400 + (35% of 400) = 400 + 140 = Rs. 540

Let numbers be 5x and 8x. 5x + 8x = 130, 13x = 130, x = 10. Larger number = 8 × 10 = 80

SI = 1440 - 1200 = 240. Rate = (SI × 100)/(P × T) = (240 × 100)/(1200 × 2) = 10%

Speed = Distance/Time = 450/5 = 90 km/h

B earns 40% of 8000 = 0.4 × 8000 = Rs. 3200

Let number = x. 0.15x = 45. x = 45/0.15 = 300

Increase = 65000 - 50000 = 15000. Percentage = (15000/50000) × 100 = 30%