-68.75% is the change from 320 to 100
Calculation steps:
[( 100 - 320 ) ÷ 320] x 100 = -68.75%
Formula
Percentage change = [(100 - 320) / 320] x 100
Subtract the new number by the original number
100 - 320 = -220
-220 ÷ 320 = -0.6875
-0.6875 x 100 = -68.75%