21.81% is the change from 321 to 391
Calculation steps:
[( 391 - 321 ) ÷ 321] x 100 = 21.81%
Formula
Percentage change = [(391 - 321) / 321] x 100
Subtract the new number by the original number
391 - 321 = 70
70 ÷ 321 = 0.21806853582554517
0.21806853582554517 x 100 = 21.81%