-8.55% is the change from 351 to 321
Calculation steps:
[( 321 - 351 ) ÷ 351] x 100 = -8.55%
Formula
Percentage change = [(321 - 351) / 351] x 100
Subtract the new number by the original number
321 - 351 = -30
-30 ÷ 351 = -0.08547008547008547
-0.08547008547008547 x 100 = -8.55%