200% is the change from 70 to 210
Calculation steps:
[( 210 - 70 ) ÷ 70] x 100 = 200%
Formula
Percentage change = [(210 - 70) / 70] x 100
Subtract the new number by the original number
210 - 70 = 140
140 ÷ 70 = 2
2 x 100 = 200%
Example