-3.42% is the change from 849 to 820
Calculation steps:
[( 820 - 849 ) ÷ 849] x 100 = -3.42%
Formula
Percentage change = [(820 - 849) / 849] x 100
Subtract the new number by the original number
820 - 849 = -29
-29 ÷ 849 = -0.03415783274440518
-0.03415783274440518 x 100 = -3.42%