-50% is the change from 60 to 30
Calculation steps:
[( 30 - 60 ) ÷ 60] x 100 = -50%
Formula
Percentage change = [(30 - 60) / 60] x 100
Subtract the new number by the original number
30 - 60 = -30
-30 ÷ 60 = -0.5
-0.5 x 100 = -50%
Example