-78.38% is the change from 421 to 91
Calculation steps:
[( 91 - 421 ) ÷ 421] x 100 = -78.38%
Formula
Percentage change = [(91 - 421) / 421] x 100
Subtract the new number by the original number
91 - 421 = -330
-330 ÷ 421 = -0.7838479809976246
-0.7838479809976246 x 100 = -78.38%