-59.04% is the change from 830 to 340
Calculation steps:
[( 340 - 830 ) ÷ 830] x 100 = -59.04%
Formula
Percentage change = [(340 - 830) / 830] x 100
Subtract the new number by the original number
340 - 830 = -490
-490 ÷ 830 = -0.5903614457831325
-0.5903614457831325 x 100 = -59.04%