A reduction in value will always result in a higher percentage change than will an addition in value. That's because the higher the base, the lower the percentage for any given change.
Reduction from 25 to 20 will result in a 20% reduction (25-20=5/25x100).
Increase from 20 to 25 will result in a 25% increase (25-20=5/20x100).
Below input the 'start' number and the 'end' number and the result automatically emerges.