-78.57% is the change from 42 to 9
Calculation steps:
[( 9 - 42 ) ÷ 42] x 100 = -78.57%
Formula
Percentage change = [(9 - 42) / 42] x 100
Subtract the new number by the original number
9 - 42 = -33
-33 ÷ 42 = -0.7857142857142857
-0.7857142857142857 x 100 = -78.57%