-14.29% is the change from 21 to 18
Calculation steps:
[( 18 - 21 ) ÷ 21] x 100 = -14.29%
Formula
Percentage change = [(18 - 21) / 21] x 100
Subtract the new number by the original number
18 - 21 = -3
-3 ÷ 21 = -0.14285714285714285
-0.14285714285714285 x 100 = -14.29%