40% is the change from 225 to 315
Calculation steps:
[( 315 - 225 ) ÷ 225] x 100 = 40%
Formula
Percentage change = [(315 - 225) / 225] x 100
Subtract the new number by the original number
315 - 225 = 90
90 ÷ 225 = 0.4
0.4 x 100 = 40%
Example