-31.7% is the change from 978 to 668
Calculation steps:
[( 668 - 978 ) ÷ 978] x 100 = -31.7%
Formula
Percentage change = [(668 - 978) / 978] x 100
Subtract the new number by the original number
668 - 978 = -310
-310 ÷ 978 = -0.3169734151329243
-0.3169734151329243 x 100 = -31.7%