-88.07% is the change from 830 to 99
Calculation steps:
[( 99 - 830 ) ÷ 830] x 100 = -88.07%
Formula
Percentage change = [(99 - 830) / 830] x 100
Subtract the new number by the original number
99 - 830 = -731
-731 ÷ 830 = -0.880722891566265
-0.880722891566265 x 100 = -88.07%