-66.6% is the change from 509 to 170
Calculation steps:
[( 170 - 509 ) ÷ 509] x 100 = -66.6%
Formula
Percentage change = [(170 - 509) / 509] x 100
Subtract the new number by the original number
170 - 509 = -339
-339 ÷ 509 = -0.6660117878192534
-0.6660117878192534 x 100 = -66.6%