50% is the change from 210 to 315
Calculation steps:
[( 315 - 210 ) ÷ 210] x 100 = 50%
Formula
Percentage change = [(315 - 210) / 210] x 100
Subtract the new number by the original number
315 - 210 = 105
105 ÷ 210 = 0.5
0.5 x 100 = 50%
Example