-90.58% is the change from 839 to 79
Calculation steps:
[( 79 - 839 ) ÷ 839] x 100 = -90.58%
Formula
Percentage change = [(79 - 839) / 839] x 100
Subtract the new number by the original number
79 - 839 = -760
-760 ÷ 839 = -0.9058402860548271
-0.9058402860548271 x 100 = -90.58%