-75% is the change from 680 to 170
Calculation steps:
[( 170 - 680 ) ÷ 680] x 100 = -75%
Formula
Percentage change = [(170 - 680) / 680] x 100
Subtract the new number by the original number
170 - 680 = -510
-510 ÷ 680 = -0.75
-0.75 x 100 = -75%
Example