-90% is the change from 320 to 32
Calculation steps:
[( 32 - 320 ) ÷ 320] x 100 = -90%
Formula
Percentage change = [(32 - 320) / 320] x 100
Subtract the new number by the original number
32 - 320 = -288
-288 ÷ 320 = -0.9
-0.9 x 100 = -90%
Example