-18.57% is the change from 210 to 171
Calculation steps:
[( 171 - 210 ) ÷ 210] x 100 = -18.57%
Formula
Percentage change = [(171 - 210) / 210] x 100
Subtract the new number by the original number
171 - 210 = -39
-39 ÷ 210 = -0.18571428571428572
-0.18571428571428572 x 100 = -18.57%