-71.65% is the change from 321 to 91
Calculation steps:
[( 91 - 321 ) ÷ 321] x 100 = -71.65%
Formula
Percentage change = [(91 - 321) / 321] x 100
Subtract the new number by the original number
91 - 321 = -230
-230 ÷ 321 = -0.7165109034267912
-0.7165109034267912 x 100 = -71.65%