-7.46% is the change from 670 to 620
Calculation steps:
[( 620 - 670 ) ÷ 670] x 100 = -7.46%
Formula
Percentage change = [(620 - 670) / 670] x 100
Subtract the new number by the original number
620 - 670 = -50
-50 ÷ 670 = -0.07462686567164178
-0.07462686567164178 x 100 = -7.46%