-80% is the change from 150 to 30
Calculation steps:
[( 30 - 150 ) ÷ 150] x 100 = -80%
Formula
Percentage change = [(30 - 150) / 150] x 100
Subtract the new number by the original number
30 - 150 = -120
-120 ÷ 150 = -0.8
-0.8 x 100 = -80%
Example