-87.91% is the change from 91 to 11
Calculation steps:
[( 11 - 91 ) ÷ 91] x 100 = -87.91%
Formula
Percentage change = [(11 - 91) / 91] x 100
Subtract the new number by the original number
11 - 91 = -80
-80 ÷ 91 = -0.8791208791208791
-0.8791208791208791 x 100 = -87.91%