-71.88% is the change from 320 to 90
Calculation steps:
[( 90 - 320 ) ÷ 320] x 100 = -71.88%
Formula
Percentage change = [(90 - 320) / 320] x 100
Subtract the new number by the original number
90 - 320 = -230
-230 ÷ 320 = -0.71875
-0.71875 x 100 = -71.88%