-38.46% is the change from 520 to 320
Calculation steps:
[( 320 - 520 ) ÷ 520] x 100 = -38.46%
Formula
Percentage change = [(320 - 520) / 520] x 100
Subtract the new number by the original number
320 - 520 = -200
-200 ÷ 520 = -0.38461538461538464
-0.38461538461538464 x 100 = -38.46%