-61.9% is the change from 21 to 8
Calculation steps:
[( 8 - 21 ) ÷ 21] x 100 = -61.9%
Formula
Percentage change = [(8 - 21) / 21] x 100
Subtract the new number by the original number
8 - 21 = -13
-13 ÷ 21 = -0.6190476190476191
-0.6190476190476191 x 100 = -61.9%