-10% is the change from 30 to 27
Calculation steps:
[( 27 - 30 ) ÷ 30] x 100 = -10%
Formula
Percentage change = [(27 - 30) / 30] x 100
Subtract the new number by the original number
27 - 30 = -3
-3 ÷ 30 = -0.1
-0.1 x 100 = -10%
Example