-27.65% is the change from 850 to 615
Calculation steps:
[( 615 - 850 ) ÷ 850] x 100 = -27.65%
Formula
Percentage change = [(615 - 850) / 850] x 100
Subtract the new number by the original number
615 - 850 = -235
-235 ÷ 850 = -0.27647058823529413
-0.27647058823529413 x 100 = -27.65%