-1.8% is the change from 835 to 820
Calculation steps:
[( 820 - 835 ) ÷ 835] x 100 = -1.8%
Formula
Percentage change = [(820 - 835) / 835] x 100
Subtract the new number by the original number
820 - 835 = -15
-15 ÷ 835 = -0.017964071856287425
-0.017964071856287425 x 100 = -1.8%