700% is the change from 80 to 640
Calculation steps:
[( 640 - 80 ) ÷ 80] x 100 = 700%
Formula
Percentage change = [(640 - 80) / 80] x 100
Subtract the new number by the original number
640 - 80 = 560
560 ÷ 80 = 7
7 x 100 = 700%
Example