-39.54% is the change from 521 to 315
Calculation steps:
[( 315 - 521 ) ÷ 521] x 100 = -39.54%
Formula
Percentage change = [(315 - 521) / 521] x 100
Subtract the new number by the original number
315 - 521 = -206
-206 ÷ 521 = -0.39539347408829173
-0.39539347408829173 x 100 = -39.54%