-21.29% is the change from 850 to 669
Calculation steps:
[( 669 - 850 ) ÷ 850] x 100 = -21.29%
Formula
Percentage change = [(669 - 850) / 850] x 100
Subtract the new number by the original number
669 - 850 = -181
-181 ÷ 850 = -0.21294117647058824
-0.21294117647058824 x 100 = -21.29%