-41.79% is the change from 670 to 390
Calculation steps:
[( 390 - 670 ) ÷ 670] x 100 = -41.79%
Formula
Percentage change = [(390 - 670) / 670] x 100
Subtract the new number by the original number
390 - 670 = -280
-280 ÷ 670 = -0.417910447761194
-0.417910447761194 x 100 = -41.79%