5100% is the change from 15 to 780
Calculation steps:
[( 780 - 15 ) ÷ 15] x 100 = 5100%
Formula
Percentage change = [(780 - 15) / 15] x 100
Subtract the new number by the original number
780 - 15 = 765
765 ÷ 15 = 51
51 x 100 = 5100%
Example