400% is the change from 70 to 350
Calculation steps:
[( 350 - 70 ) ÷ 70] x 100 = 400%
Formula
Percentage change = [(350 - 70) / 70] x 100
Subtract the new number by the original number
350 - 70 = 280
280 ÷ 70 = 4
4 x 100 = 400%
Example