-17.91% is the change from 670 to 550
Calculation steps:
[( 550 - 670 ) ÷ 670] x 100 = -17.91%
Formula
Percentage change = [(550 - 670) / 670] x 100
Subtract the new number by the original number
550 - 670 = -120
-120 ÷ 670 = -0.1791044776119403
-0.1791044776119403 x 100 = -17.91%