Understanding the Problem: Salary, Savings, and Expenditure

The question asks us to find the monthly expenditure of Mrs. Deepa Devi. We are given her total monthly salary and the percentage of her salary that she saves. To find the expenditure, we need to first calculate the amount she saves and then subtract that amount from her total salary.

Here are the key pieces of information provided:

• Monthly Salary: Rs. 42,000
• Percentage of Salary Saved: 30%

The relationship between salary, savings, and expenditure is:

Salary = Savings + Expenditure

Therefore, to find the expenditure, we can rearrange the formula:

Expenditure = Salary - Savings

Calculating Monthly Savings

Mrs. Deepa Devi saves 30% of her monthly salary. To calculate the amount saved, we need to find 30% of Rs. 42,000.

Percentage means 'out of 100', so 30% can be written as \(\frac{30}{100}\).

Amount Saved = 30% of Rs. 42,000

Amount Saved \( = \frac{30}{100} \times 42000 \)

We can simplify this calculation:

\( = 30 \times \frac{42000}{100} \)

\( = 30 \times 420 \)

Let's calculate \(30 \times 420\):

\( 30 \times 420 = 12600 \)

So, Mrs. Deepa Devi saves Rs. 12,600 per month.

Determining Monthly Expenditure

Now that we know her total salary and the amount she saves, we can find her expenditure using the formula:

Expenditure = Salary - Savings

Expenditure = Rs. 42,000 - Rs. 12,600

Expenditure \( = 42000 - 12600 \)

Let's perform the subtraction:

\( 42000 \)
\( - 12600 \)
\( \rule{4em}{0.4pt} \)
\( 29400 \)

Her monthly expenditure is Rs. 29,400.

Summary of Calculation Steps

1. Identify the total monthly salary (Rs. 42,000).
2. Identify the percentage of salary saved (30%).
3. Calculate the amount saved by finding 30% of the salary: \( 0.30 \times 42000 = 12600 \).
4. Calculate the monthly expenditure by subtracting the savings from the salary: \( 42000 - 12600 = 29400 \).

Thus, Mrs. Deepa Devi's monthly expenditure is Rs. 29,400.

Revision Table: Understanding Percentages and Personal Finance

Additional Information: Budgeting Basics

Understanding salary, savings, and expenditure is fundamental to personal budgeting. A budget helps you manage your money effectively by planning how to spend and save.

• Income: This is the money you receive, primarily your salary.
• Expenses (Expenditure): These are the costs you incur for goods and services (rent, food, transport, entertainment, etc.).
• Savings: The portion of your income that you set aside, often for specific goals (emergency fund, down payment, retirement).

A common budgeting guideline is the 50/30/20 rule, where 50% of income goes to needs (essential expenditure), 30% to wants (non-essential expenditure), and 20% to savings and debt repayment. In this problem, Mrs. Deepa Devi saves 30%, meaning her expenditure (needs + wants) is 70%.

Calculating 70% of Rs. 42,000:

\( 70\% \text{ of } 42000 = \frac{70}{100} \times 42000 = 70 \times 420 = 29400 \)

This confirms our previous calculation that her expenditure is Rs. 29,400.