-48.5% is the change from 666 to 343
Calculation steps:
[( 343 - 666 ) ÷ 666] x 100 = -48.5%
Formula
Percentage change = [(343 - 666) / 666] x 100
Subtract the new number by the original number
343 - 666 = -323
-323 ÷ 666 = -0.484984984984985
-0.484984984984985 x 100 = -48.5%