-57.5% is the change from 800 to 340
Calculation steps:
[( 340 - 800 ) ÷ 800] x 100 = -57.5%
Formula
Percentage change = [(340 - 800) / 800] x 100
Subtract the new number by the original number
340 - 800 = -460
-460 ÷ 800 = -0.575
-0.575 x 100 = -57.5%