20.9% is the change from 670 to 810
Calculation steps:
[( 810 - 670 ) ÷ 670] x 100 = 20.9%
Formula
Percentage change = [(810 - 670) / 670] x 100
Subtract the new number by the original number
810 - 670 = 140
140 ÷ 670 = 0.208955223880597
0.208955223880597 x 100 = 20.9%