-50.3% is the change from 660 to 328
Calculation steps:
[( 328 - 660 ) ÷ 660] x 100 = -50.3%
Formula
Percentage change = [(328 - 660) / 660] x 100
Subtract the new number by the original number
328 - 660 = -332
-332 ÷ 660 = -0.503030303030303
-0.503030303030303 x 100 = -50.3%