Question

A person saves 10% of his income if his income increases by 20% and he decides to save 15% of his income by what per cent has his saving increased

Answer 1

let's say initial income = 100
savings is 10%
i.e. savings = 10

income is increased by 20%
new income = 120
new savings = 15%
15% of 120 = 18

increase in income = 18-10
=8
As we've assumed income to be 100,
it will be 8% [( change/initial income)*100 ]

Answer 2

10×x/100
=x
20×x/100
=2x
15×2x/100
=30
I hope you understand my answer