100% is the change from 85 to 170
Calculation steps:
[( 170 - 85 ) ÷ 85] x 100 = 100%
Formula
Percentage change = [(170 - 85) / 85] x 100
Subtract the new number by the original number
170 - 85 = 85
85 ÷ 85 = 1
1 x 100 = 100%
Example