-70.18% is the change from 171 to 51
Calculation steps:
[( 51 - 171 ) ÷ 171] x 100 = -70.18%
Formula
Percentage change = [(51 - 171) / 171] x 100
Subtract the new number by the original number
51 - 171 = -120
-120 ÷ 171 = -0.7017543859649122
-0.7017543859649122 x 100 = -70.18%