700% is the change from 40 to 320
Calculation steps:
[( 320 - 40 ) ÷ 40] x 100 = 700%
Formula
Percentage change = [(320 - 40) / 40] x 100
Subtract the new number by the original number
320 - 40 = 280
280 ÷ 40 = 7
7 x 100 = 700%
Example