-81.93% is the change from 83 to 15
Calculation steps:
[( 15 - 83 ) ÷ 83] x 100 = -81.93%
Formula
Percentage change = [(15 - 83) / 83] x 100
Subtract the new number by the original number
15 - 83 = -68
-68 ÷ 83 = -0.8192771084337349
-0.8192771084337349 x 100 = -81.93%