211.11% is the change from 9 to 28
Calculation steps:
[( 28 - 9 ) ÷ 9] x 100 = 211.11%
Formula
Percentage change = [(28 - 9) / 9] x 100
Subtract the new number by the original number
28 - 9 = 19
19 ÷ 9 = 2.111111111111111
2.111111111111111 x 100 = 211.11%