-42.86% is the change from 70 to 40
Calculation steps:
[( 40 - 70 ) ÷ 70] x 100 = -42.86%
Formula
Percentage change = [(40 - 70) / 70] x 100
Subtract the new number by the original number
40 - 70 = -30
-30 ÷ 70 = -0.42857142857142855
-0.42857142857142855 x 100 = -42.86%