-22.22% is the change from 90 to 70
Calculation steps:
[( 70 - 90 ) ÷ 90] x 100 = -22.22%
Formula
Percentage change = [(70 - 90) / 90] x 100
Subtract the new number by the original number
70 - 90 = -20
-20 ÷ 90 = -0.2222222222222222
-0.2222222222222222 x 100 = -22.22%