21.09% is the change from 640 to 775
Calculation steps:
[( 775 - 640 ) ÷ 640] x 100 = 21.09%
Formula
Percentage change = [(775 - 640) / 640] x 100
Subtract the new number by the original number
775 - 640 = 135
135 ÷ 640 = 0.2109375
0.2109375 x 100 = 21.09%