-71.43% is the change from 21 to 6
Calculation steps:
[( 6 - 21 ) ÷ 21] x 100 = -71.43%
Formula
Percentage change = [(6 - 21) / 21] x 100
Subtract the new number by the original number
6 - 21 = -15
-15 ÷ 21 = -0.7142857142857143
-0.7142857142857143 x 100 = -71.43%