-17.32% is the change from 231 to 191
Calculation steps:
[( 191 - 231 ) ÷ 231] x 100 = -17.32%
Formula
Percentage change = [(191 - 231) / 231] x 100
Subtract the new number by the original number
191 - 231 = -40
-40 ÷ 231 = -0.17316017316017315
-0.17316017316017315 x 100 = -17.32%