83.33% is the change from 420 to 770
Calculation steps:
[( 770 - 420 ) ÷ 420] x 100 = 83.33%
Formula
Percentage change = [(770 - 420) / 420] x 100
Subtract the new number by the original number
770 - 420 = 350
350 ÷ 420 = 0.8333333333333334
0.8333333333333334 x 100 = 83.33%