-23.08% is the change from 390 to 300
Calculation steps:
[( 300 - 390 ) ÷ 390] x 100 = -23.08%
Formula
Percentage change = [(300 - 390) / 390] x 100
Subtract the new number by the original number
300 - 390 = -90
-90 ÷ 390 = -0.23076923076923078
-0.23076923076923078 x 100 = -23.08%