Amina saves $16\%$ of her income. Now her income is increased by $20\%$ but she still saves the same amount as before. What is the percentage increase in her expenditure?

Let Amina's initial income be $\text{₹}100$.Initial Savings = $16\%\text{ of }100=\text{₹}16$ Initial Expenditure = $\text{Income}-\text{Savings}=100-16=\text{₹}84$ Now, her income increases by $20\%$:New Income = $100+20\%\text{ of }100=\text{₹}120$ Her savings remain the same as before:New Savings = $\text{₹}16$ Therefore, her new expenditure is:New Expenditure = $\text{New Income}-\text{New Savings}=120-16=\text{₹}104$ The increase in expenditure is:
$$\text{Increase in Expenditure}=104-84=\text{₹}20$$
Percentage increase in expenditure:
$$\text{Percentage Increase}=\frac{20}{84}\times 100=\frac{5}{21}\times 100=\frac{500}{21}\approx 23.8\%$$