-28.57% is the change from 70 to 50
Calculation steps:
[( 50 - 70 ) ÷ 70] x 100 = -28.57%
Formula
Percentage change = [(50 - 70) / 70] x 100
Subtract the new number by the original number
50 - 70 = -20
-20 ÷ 70 = -0.2857142857142857
-0.2857142857142857 x 100 = -28.57%