-24.79% is the change from 121 to 91
Calculation steps:
[( 91 - 121 ) ÷ 121] x 100 = -24.79%
Formula
Percentage change = [(91 - 121) / 121] x 100
Subtract the new number by the original number
91 - 121 = -30
-30 ÷ 121 = -0.24793388429752067
-0.24793388429752067 x 100 = -24.79%