-20% is the change from 45 to 36
Calculation steps:
[( 36 - 45 ) ÷ 45] x 100 = -20%
Formula
Percentage change = [(36 - 45) / 45] x 100
Subtract the new number by the original number
36 - 45 = -9
-9 ÷ 45 = -0.2
-0.2 x 100 = -20%
Example