-50% is the change from 140 to 70
Calculation steps:
[( 70 - 140 ) ÷ 140] x 100 = -50%
Formula
Percentage change = [(70 - 140) / 140] x 100
Subtract the new number by the original number
70 - 140 = -70
-70 ÷ 140 = -0.5
-0.5 x 100 = -50%
Example