-9.36% is the change from 171 to 155
Calculation steps:
[( 155 - 171 ) ÷ 171] x 100 = -9.36%
Formula
Percentage change = [(155 - 171) / 171] x 100
Subtract the new number by the original number
155 - 171 = -16
-16 ÷ 171 = -0.0935672514619883
-0.0935672514619883 x 100 = -9.36%