100% is the change from 30 to 60
Calculation steps:
[( 60 - 30 ) ÷ 30] x 100 = 100%
Formula
Percentage change = [(60 - 30) / 30] x 100
Subtract the new number by the original number
60 - 30 = 30
30 ÷ 30 = 1
1 x 100 = 100%
Example