-3.61% is the change from 830 to 800
Calculation steps:
[( 800 - 830 ) ÷ 830] x 100 = -3.61%
Formula
Percentage change = [(800 - 830) / 830] x 100
Subtract the new number by the original number
800 - 830 = -30
-30 ÷ 830 = -0.03614457831325301
-0.03614457831325301 x 100 = -3.61%