20% is the change from 350 to 420
Calculation steps:
[( 420 - 350 ) ÷ 350] x 100 = 20%
Formula
Percentage change = [(420 - 350) / 350] x 100
Subtract the new number by the original number
420 - 350 = 70
70 ÷ 350 = 0.2
0.2 x 100 = 20%
Example