-71.96% is the change from 321 to 90
Calculation steps:
[( 90 - 321 ) ÷ 321] x 100 = -71.96%
Formula
Percentage change = [(90 - 321) / 321] x 100
Subtract the new number by the original number
90 - 321 = -231
-231 ÷ 321 = -0.719626168224299
-0.719626168224299 x 100 = -71.96%