-81.1% is the change from 815 to 154
Calculation steps:
[( 154 - 815 ) ÷ 815] x 100 = -81.1%
Formula
Percentage change = [(154 - 815) / 815] x 100
Subtract the new number by the original number
154 - 815 = -661
-661 ÷ 815 = -0.811042944785276
-0.811042944785276 x 100 = -81.1%