-24.79% is the change from 851 to 640
Calculation steps:
[( 640 - 851 ) ÷ 851] x 100 = -24.79%
Formula
Percentage change = [(640 - 851) / 851] x 100
Subtract the new number by the original number
640 - 851 = -211
-211 ÷ 851 = -0.24794359576968272
-0.24794359576968272 x 100 = -24.79%