300% is the change from 85 to 340
Calculation steps:
[( 340 - 85 ) ÷ 85] x 100 = 300%
Formula
Percentage change = [(340 - 85) / 85] x 100
Subtract the new number by the original number
340 - 85 = 255
255 ÷ 85 = 3
3 x 100 = 300%
Example