-22.73% is the change from 220 to 170
Calculation steps:
[( 170 - 220 ) ÷ 220] x 100 = -22.73%
Formula
Percentage change = [(170 - 220) / 220] x 100
Subtract the new number by the original number
170 - 220 = -50
-50 ÷ 220 = -0.22727272727272727
-0.22727272727272727 x 100 = -22.73%