-50.24% is the change from 615 to 306
Calculation steps:
[( 306 - 615 ) ÷ 615] x 100 = -50.24%
Formula
Percentage change = [(306 - 615) / 615] x 100
Subtract the new number by the original number
306 - 615 = -309
-309 ÷ 615 = -0.5024390243902439
-0.5024390243902439 x 100 = -50.24%