-60% is the change from 30 to 12
Calculation steps:
[( 12 - 30 ) ÷ 30] x 100 = -60%
Formula
Percentage change = [(12 - 30) / 30] x 100
Subtract the new number by the original number
12 - 30 = -18
-18 ÷ 30 = -0.6
-0.6 x 100 = -60%
Example