-31.56% is the change from 320 to 219
Calculation steps:
[( 219 - 320 ) ÷ 320] x 100 = -31.56%
Formula
Percentage change = [(219 - 320) / 320] x 100
Subtract the new number by the original number
219 - 320 = -101
-101 ÷ 320 = -0.315625
-0.315625 x 100 = -31.56%