-83% is the change from 800 to 136
Calculation steps:
[( 136 - 800 ) ÷ 800] x 100 = -83%
Formula
Percentage change = [(136 - 800) / 800] x 100
Subtract the new number by the original number
136 - 800 = -664
-664 ÷ 800 = -0.83
-0.83 x 100 = -83%
Example