259.3% is the change from 86 to 309
Calculation steps:
[( 309 - 86 ) ÷ 86] x 100 = 259.3%
Formula
Percentage change = [(309 - 86) / 86] x 100
Subtract the new number by the original number
309 - 86 = 223
223 ÷ 86 = 2.5930232558139537
2.5930232558139537 x 100 = 259.3%