-29.4% is the change from 915 to 646
Calculation steps:
[( 646 - 915 ) ÷ 915] x 100 = -29.4%
Formula
Percentage change = [(646 - 915) / 915] x 100
Subtract the new number by the original number
646 - 915 = -269
-269 ÷ 915 = -0.2939890710382514
-0.2939890710382514 x 100 = -29.4%