-16.51% is the change from 109 to 91
Calculation steps:
[( 91 - 109 ) ÷ 109] x 100 = -16.51%
Formula
Percentage change = [(91 - 109) / 109] x 100
Subtract the new number by the original number
91 - 109 = -18
-18 ÷ 109 = -0.1651376146788991
-0.1651376146788991 x 100 = -16.51%