40% is the change from 50 to 70
Calculation steps:
[( 70 - 50 ) ÷ 50] x 100 = 40%
Formula
Percentage change = [(70 - 50) / 50] x 100
Subtract the new number by the original number
70 - 50 = 20
20 ÷ 50 = 0.4
0.4 x 100 = 40%
Example