-3.88% is the change from 850 to 817
Calculation steps:
[( 817 - 850 ) ÷ 850] x 100 = -3.88%
Formula
Percentage change = [(817 - 850) / 850] x 100
Subtract the new number by the original number
817 - 850 = -33
-33 ÷ 850 = -0.03882352941176471
-0.03882352941176471 x 100 = -3.88%