-61.45% is the change from 830 to 320
Calculation steps:
[( 320 - 830 ) ÷ 830] x 100 = -61.45%
Formula
Percentage change = [(320 - 830) / 830] x 100
Subtract the new number by the original number
320 - 830 = -510
-510 ÷ 830 = -0.6144578313253012
-0.6144578313253012 x 100 = -61.45%