-20% is the change from 635 to 508
Calculation steps:
[( 508 - 635 ) ÷ 635] x 100 = -20%
Formula
Percentage change = [(508 - 635) / 635] x 100
Subtract the new number by the original number
508 - 635 = -127
-127 ÷ 635 = -0.2
-0.2 x 100 = -20%
Example