-40.35% is the change from 850 to 507
Calculation steps:
[( 507 - 850 ) ÷ 850] x 100 = -40.35%
Formula
Percentage change = [(507 - 850) / 850] x 100
Subtract the new number by the original number
507 - 850 = -343
-343 ÷ 850 = -0.40352941176470586
-0.40352941176470586 x 100 = -40.35%