-58.21% is the change from 670 to 280
Calculation steps:
[( 280 - 670 ) ÷ 670] x 100 = -58.21%
Formula
Percentage change = [(280 - 670) / 670] x 100
Subtract the new number by the original number
280 - 670 = -390
-390 ÷ 670 = -0.582089552238806
-0.582089552238806 x 100 = -58.21%