-74.7% is the change from 830 to 210
Calculation steps:
[( 210 - 830 ) ÷ 830] x 100 = -74.7%
Formula
Percentage change = [(210 - 830) / 830] x 100
Subtract the new number by the original number
210 - 830 = -620
-620 ÷ 830 = -0.7469879518072289
-0.7469879518072289 x 100 = -74.7%