-21.98% is the change from 91 to 71
Calculation steps:
[( 71 - 91 ) ÷ 91] x 100 = -21.98%
Formula
Percentage change = [(71 - 91) / 91] x 100
Subtract the new number by the original number
71 - 91 = -20
-20 ÷ 91 = -0.21978021978021978
-0.21978021978021978 x 100 = -21.98%