-85.71% is the change from 21 to 3
Calculation steps:
[( 3 - 21 ) ÷ 21] x 100 = -85.71%
Formula
Percentage change = [(3 - 21) / 21] x 100
Subtract the new number by the original number
3 - 21 = -18
-18 ÷ 21 = -0.8571428571428571
-0.8571428571428571 x 100 = -85.71%