-29.84% is the change from 915 to 642
Calculation steps:
[( 642 - 915 ) ÷ 915] x 100 = -29.84%
Formula
Percentage change = [(642 - 915) / 915] x 100
Subtract the new number by the original number
642 - 915 = -273
-273 ÷ 915 = -0.2983606557377049
-0.2983606557377049 x 100 = -29.84%