-86.81% is the change from 91 to 12
Calculation steps:
[( 12 - 91 ) ÷ 91] x 100 = -86.81%
Formula
Percentage change = [(12 - 91) / 91] x 100
Subtract the new number by the original number
12 - 91 = -79
-79 ÷ 91 = -0.8681318681318682
-0.8681318681318682 x 100 = -86.81%