-20.05% is the change from 798 to 638
Calculation steps:
[( 638 - 798 ) ÷ 798] x 100 = -20.05%
Formula
Percentage change = [(638 - 798) / 798] x 100
Subtract the new number by the original number
638 - 798 = -160
-160 ÷ 798 = -0.20050125313283207
-0.20050125313283207 x 100 = -20.05%