250% is the change from 20 to 70
Calculation steps:
[( 70 - 20 ) ÷ 20] x 100 = 250%
Formula
Percentage change = [(70 - 20) / 20] x 100
Subtract the new number by the original number
70 - 20 = 50
50 ÷ 20 = 2.5
2.5 x 100 = 250%
Example