-8.9% is the change from 236 to 215
Calculation steps:
[( 215 - 236 ) ÷ 236] x 100 = -8.9%
Formula
Percentage change = [(215 - 236) / 236] x 100
Subtract the new number by the original number
215 - 236 = -21
-21 ÷ 236 = -0.08898305084745763
-0.08898305084745763 x 100 = -8.9%