-46.78% is the change from 171 to 91
Calculation steps:
[( 91 - 171 ) ÷ 171] x 100 = -46.78%
Formula
Percentage change = [(91 - 171) / 171] x 100
Subtract the new number by the original number
91 - 171 = -80
-80 ÷ 171 = -0.4678362573099415
-0.4678362573099415 x 100 = -46.78%