425% is the change from 80 to 420
Calculation steps:
[( 420 - 80 ) ÷ 80] x 100 = 425%
Formula
Percentage change = [(420 - 80) / 80] x 100
Subtract the new number by the original number
420 - 80 = 340
340 ÷ 80 = 4.25
4.25 x 100 = 425%
Example