42.97% is the change from 640 to 915
Calculation steps:
[( 915 - 640 ) ÷ 640] x 100 = 42.97%
Formula
Percentage change = [(915 - 640) / 640] x 100
Subtract the new number by the original number
915 - 640 = 275
275 ÷ 640 = 0.4296875
0.4296875 x 100 = 42.97%