15.71% is the change from 70 to 81
Calculation steps:
[( 81 - 70 ) ÷ 70] x 100 = 15.71%
Formula
Percentage change = [(81 - 70) / 70] x 100
Subtract the new number by the original number
81 - 70 = 11
11 ÷ 70 = 0.15714285714285714
0.15714285714285714 x 100 = 15.71%