-8.51% is the change from 235 to 215
Calculation steps:
[( 215 - 235 ) ÷ 235] x 100 = -8.51%
Formula
Percentage change = [(215 - 235) / 235] x 100
Subtract the new number by the original number
215 - 235 = -20
-20 ÷ 235 = -0.0851063829787234
-0.0851063829787234 x 100 = -8.51%