Renu saves 20% of her income. If her expenditure increase by 20% and income increase by 29%, then her saving increase by:

Answer: Option B

\begin{array}{*{20}{c}} {{\text{Income}}}&{{\text{Expenditure}}}& = &{{\text{Saving}}} \\ \begin{gathered} 100 \hfill \\ \,\, \downarrow \hfill \\ 129 \hfill \\ \end{gathered} &\begin{gathered} 80 \hfill \\ \, \downarrow \hfill \\ 96 \hfill \\ \end{gathered} &{}&{\left. \begin{gathered} 20 \hfill \\ \, \downarrow \hfill \\ 33 \hfill \\ \end{gathered} \right)13} \end{array}
$$\frac{13}{20}\times 100=65\%$$

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Alternate Solution :

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First, let's assume Renu's initial income is Rs. 100 (we can pick any number, 100 makes the math easier).

If she saves 20%, her initial savings are 20% of Rs. 100 = Rs. 20.

Her initial expenditure is then Rs. 100 (income) - Rs. 20 (savings) = Rs. 80.

Now, her expenditure increases by 20%. So, the increase in expenditure is 20% of Rs. 80 = Rs. 16.

Her new expenditure is Rs. 80 + Rs. 16 = Rs. 96.

Her income also increases, by 29%. So, the increase in income is 29% of Rs. 100 = Rs. 29.

Her new income is Rs. 100 + Rs. 29 = Rs. 129.

Her new savings are now Rs. 129 (new income) - Rs. 96 (new expenditure) = Rs. 33.

To find the percentage increase in savings, we compare the new savings to the old savings.

The increase in savings is Rs. 33 (new savings) - Rs. 20 (old savings) = Rs. 13.

The percentage increase in savings is (Increase in savings / Original savings) * 100 = (Rs. 13 / Rs. 20) * 100 = 65%.

Therefore, her saving increases by 65%.

The correct answer is Option B: 65%.