-21.05% is the change from 19 to 15
Calculation steps:
[( 15 - 19 ) ÷ 19] x 100 = -21.05%
Formula
Percentage change = [(15 - 19) / 19] x 100
Subtract the new number by the original number
15 - 19 = -4
-4 ÷ 19 = -0.21052631578947367
-0.21052631578947367 x 100 = -21.05%