-1.75% is the change from 855 to 840
Calculation steps:
[( 840 - 855 ) ÷ 855] x 100 = -1.75%
Formula
Percentage change = [(840 - 855) / 855] x 100
Subtract the new number by the original number
840 - 855 = -15
-15 ÷ 855 = -0.017543859649122806
-0.017543859649122806 x 100 = -1.75%