-39.7% is the change from 864 to 521
Calculation steps:
[( 521 - 864 ) ÷ 864] x 100 = -39.7%
Formula
Percentage change = [(521 - 864) / 864] x 100
Subtract the new number by the original number
521 - 864 = -343
-343 ÷ 864 = -0.39699074074074076
-0.39699074074074076 x 100 = -39.7%