-90.05% is the change from 915 to 91
Calculation steps:
[( 91 - 915 ) ÷ 915] x 100 = -90.05%
Formula
Percentage change = [(91 - 915) / 915] x 100
Subtract the new number by the original number
91 - 915 = -824
-824 ÷ 915 = -0.9005464480874317
-0.9005464480874317 x 100 = -90.05%