-77.5% is the change from 80 to 18
Calculation steps:
[( 18 - 80 ) ÷ 80] x 100 = -77.5%
Formula
Percentage change = [(18 - 80) / 80] x 100
Subtract the new number by the original number
18 - 80 = -62
-62 ÷ 80 = -0.775
-0.775 x 100 = -77.5%
Example