-6.49% is the change from 308 to 288
Calculation steps:
[( 288 - 308 ) ÷ 308] x 100 = -6.49%
Formula
Percentage change = [(288 - 308) / 308] x 100
Subtract the new number by the original number
288 - 308 = -20
-20 ÷ 308 = -0.06493506493506493
-0.06493506493506493 x 100 = -6.49%