22.19% is the change from 320 to 391
Calculation steps:
[( 391 - 320 ) ÷ 320] x 100 = 22.19%
Formula
Percentage change = [(391 - 320) / 320] x 100
Subtract the new number by the original number
391 - 320 = 71
71 ÷ 320 = 0.221875
0.221875 x 100 = 22.19%