A person saves $x$ % of her income.  If her income increases by 26% and the expenditure increases by 20%, then her savings increase by 50%.  What is the value of $x$ ?

20

Let Income = 100

Savings = Rs. $x$ 

Expenditure = 100 - $x$ 

ATQ,

Income increased = 100 × 26% = 26

Expenditure Increased = (100 - $x$ ) × 20%

Saving Increased = $x$ × 50%

Now,

Income = Expenditure + Savings

26 = {(100 - $x$ ) × 20%} + {$x$ × 50%}

26 = 20 - {$x$ × 50% - $x$ × 20%}

26 - 20 = $x$ × 30%

6 = $x$ × 30%

$x$ = 20