42.86% is the change from 21 to 30
Calculation steps:
[( 30 - 21 ) ÷ 21] x 100 = 42.86%
Formula
Percentage change = [(30 - 21) / 21] x 100
Subtract the new number by the original number
30 - 21 = 9
9 ÷ 21 = 0.42857142857142855
0.42857142857142855 x 100 = 42.86%