-25% is the change from 320 to 240
Calculation steps:
[( 240 - 320 ) ÷ 320] x 100 = -25%
Formula
Percentage change = [(240 - 320) / 320] x 100
Subtract the new number by the original number
240 - 320 = -80
-80 ÷ 320 = -0.25
-0.25 x 100 = -25%
Example