-78.02% is the change from 91 to 20
Calculation steps:
[( 20 - 91 ) ÷ 91] x 100 = -78.02%
Formula
Percentage change = [(20 - 91) / 91] x 100
Subtract the new number by the original number
20 - 91 = -71
-71 ÷ 91 = -0.7802197802197802
-0.7802197802197802 x 100 = -78.02%