-3.64% is the change from 851 to 820
Calculation steps:
[( 820 - 851 ) ÷ 851] x 100 = -3.64%
Formula
Percentage change = [(820 - 851) / 851] x 100
Subtract the new number by the original number
820 - 851 = -31
-31 ÷ 851 = -0.036427732079905996
-0.036427732079905996 x 100 = -3.64%