-97.5% is the change from 280 to 7
Calculation steps:
[( 7 - 280 ) ÷ 280] x 100 = -97.5%
Formula
Percentage change = [(7 - 280) / 280] x 100
Subtract the new number by the original number
7 - 280 = -273
-273 ÷ 280 = -0.975
-0.975 x 100 = -97.5%
Example