-10.99% is the change from 191 to 170
Calculation steps:
[( 170 - 191 ) ÷ 191] x 100 = -10.99%
Formula
Percentage change = [(170 - 191) / 191] x 100
Subtract the new number by the original number
170 - 191 = -21
-21 ÷ 191 = -0.1099476439790576
-0.1099476439790576 x 100 = -10.99%