-15% is the change from 360 to 306
Calculation steps:
[( 306 - 360 ) ÷ 360] x 100 = -15%
Formula
Percentage change = [(306 - 360) / 360] x 100
Subtract the new number by the original number
306 - 360 = -54
-54 ÷ 360 = -0.15
-0.15 x 100 = -15%
Example