34.96% is the change from 615 to 830
Calculation steps:
[( 830 - 615 ) ÷ 615] x 100 = 34.96%
Formula
Percentage change = [(830 - 615) / 615] x 100
Subtract the new number by the original number
830 - 615 = 215
215 ÷ 615 = 0.34959349593495936
0.34959349593495936 x 100 = 34.96%