-29.51% is the change from 305 to 215
Calculation steps:
[( 215 - 305 ) ÷ 305] x 100 = -29.51%
Formula
Percentage change = [(215 - 305) / 305] x 100
Subtract the new number by the original number
215 - 305 = -90
-90 ÷ 305 = -0.29508196721311475
-0.29508196721311475 x 100 = -29.51%