-86.36% is the change from 66 to 9
Calculation steps:
[( 9 - 66 ) ÷ 66] x 100 = -86.36%
Formula
Percentage change = [(9 - 66) / 66] x 100
Subtract the new number by the original number
9 - 66 = -57
-57 ÷ 66 = -0.8636363636363636
-0.8636363636363636 x 100 = -86.36%