-87.79% is the change from 172 to 21
Calculation steps:
[( 21 - 172 ) ÷ 172] x 100 = -87.79%
Formula
Percentage change = [(21 - 172) / 172] x 100
Subtract the new number by the original number
21 - 172 = -151
-151 ÷ 172 = -0.877906976744186
-0.877906976744186 x 100 = -87.79%