-95.31% is the change from 320 to 15
Calculation steps:
[( 15 - 320 ) ÷ 320] x 100 = -95.31%
Formula
Percentage change = [(15 - 320) / 320] x 100
Subtract the new number by the original number
15 - 320 = -305
-305 ÷ 320 = -0.953125
-0.953125 x 100 = -95.31%