-40% is the change from 450 to 270
Calculation steps:
[( 270 - 450 ) ÷ 450] x 100 = -40%
Formula
Percentage change = [(270 - 450) / 450] x 100
Subtract the new number by the original number
270 - 450 = -180
-180 ÷ 450 = -0.4
-0.4 x 100 = -40%
Example