-89.79% is the change from 970 to 99
Calculation steps:
[( 99 - 970 ) ÷ 970] x 100 = -89.79%
Formula
Percentage change = [(99 - 970) / 970] x 100
Subtract the new number by the original number
99 - 970 = -871
-871 ÷ 970 = -0.8979381443298969
-0.8979381443298969 x 100 = -89.79%