-19.9% is the change from 824 to 660
Calculation steps:
[( 660 - 824 ) ÷ 824] x 100 = -19.9%
Formula
Percentage change = [(660 - 824) / 824] x 100
Subtract the new number by the original number
660 - 824 = -164
-164 ÷ 824 = -0.19902912621359223
-0.19902912621359223 x 100 = -19.9%