If A's salary is 25% more than that of B, then how much percent is B's salary…

Concept: When one quantity A is p% more than another quantity B, the percentage by which B is less than A is NOT the same number p — it is p / (100 + p) × 100, because the base of comparison shifts from B to A when the direction of comparison reverses.

1. Assume B's salary as 100 units (a convenient base).

2. Since A's salary is 25% more than B's, A's salary = 100 + 25% of 100 = 125 units.

3. The difference between the two salaries = 125 − 100 = 25 units.

4. For "B less than A", the reference (base) amount is A's salary, 125 units. So the required percentage = (25 / 125) × 100 = 20%.

Cross-check: using the general relation p / (100 + p) × 100 with p = 25, we get 25 / 125 × 100 = 20%, independently confirming the same result.