-40% is the change from 150 to 90
Calculation steps:
[( 90 - 150 ) ÷ 150] x 100 = -40%
Formula
Percentage change = [(90 - 150) / 150] x 100
Subtract the new number by the original number
90 - 150 = -60
-60 ÷ 150 = -0.4
-0.4 x 100 = -40%
Example