-1.25% is the change from 800 to 790
Calculation steps:
[( 790 - 800 ) ÷ 800] x 100 = -1.25%
Formula
Percentage change = [(790 - 800) / 800] x 100
Subtract the new number by the original number
790 - 800 = -10
-10 ÷ 800 = -0.0125
-0.0125 x 100 = -1.25%