-61.54% is the change from 39 to 15
Calculation steps:
[( 15 - 39 ) ÷ 39] x 100 = -61.54%
Formula
Percentage change = [(15 - 39) / 39] x 100
Subtract the new number by the original number
15 - 39 = -24
-24 ÷ 39 = -0.6153846153846154
-0.6153846153846154 x 100 = -61.54%