-28% is the change from 850 to 612
Calculation steps:
[( 612 - 850 ) ÷ 850] x 100 = -28%
Formula
Percentage change = [(612 - 850) / 850] x 100
Subtract the new number by the original number
612 - 850 = -238
-238 ÷ 850 = -0.28
-0.28 x 100 = -28%
Example