-10% is the change from 270 to 243
Calculation steps:
[( 243 - 270 ) ÷ 270] x 100 = -10%
Formula
Percentage change = [(243 - 270) / 270] x 100
Subtract the new number by the original number
243 - 270 = -27
-27 ÷ 270 = -0.1
-0.1 x 100 = -10%
Example