-20.9% is the change from 402 to 318
Calculation steps:
[( 318 - 402 ) ÷ 402] x 100 = -20.9%
Formula
Percentage change = [(318 - 402) / 402] x 100
Subtract the new number by the original number
318 - 402 = -84
-84 ÷ 402 = -0.208955223880597
-0.208955223880597 x 100 = -20.9%