Question

How can you solve real-world problems using decimal addition or decimal subtraction?

Answer 1

Solving real-world problems using decimal addition or subtraction is common in various scenarios. Here are a few examples and methods on how to apply these operations effectively:

### 1. **Financial Transactions**
- **Example: Budgeting**
If you have a monthly budget of $2500 and you plan to spend $1234.50 on rent and $765.25 on groceries, you can find out how much money you have left by using subtraction:
\[
2500 - (1234.50 + 765.25) = 2500 - 1999.75 = 500.25
\]
- **Example: Purchase Total**
If you buy several items costing $15.99, $29.50, and $8.75, add these amounts to find the total you spent:
\[
15.99 + 29.50 + 8.75 = 54.24
\]

### 2. **Measurement and Construction**
- **Example: Home Renovations**
When planning a renovation, if you have a total space of 120.5 square meters and you plan to use 45.75 square meters for a living room and 30.25 square meters for a kitchen, you can find out the remaining area:
\[
120.5 - (45.75 + 30.25) = 120.5 - 76 = 44.5 \text{ square meters}
\]

### 3. **Cooking and Recipes**
- **Example: Ingredients Measurement**
If a recipe calls for 2.5 cups of flour and you already have 1.75 cups, you would use subtraction to figure out how much more flour you need:
\[
2.5 - 1.75 = 0.75 \text{ cups}
\]

### 4. **Time Management**
- **Example: Scheduling**
If a meeting is scheduled for 1.75 hours and it starts at 9:00 AM, you can find out when the meeting ends by adding:
\[
9:00 \text{ AM} + 1.75 \text{ hours} = 10:45 \text{ AM}
\]

### 5. **Shopping Discounts**
- **Example: Applying Discounts**
If an item costs $85.00 and is on sale for 20% off, first calculate the discount ($85.00 * 0.20 = $17.00) and then subtract it from the original price to find the sale price:
\[
85.00 - 17.00 = 68.00
\]

### 6. **Travel Distance and Fuel Calculations**
- **Example: Fuel Consumption**
If you're going on a trip that covers 150.75 miles and your car gets 25 miles per gallon of fuel, you need to calculate how many gallons will be required:
\[
\text{Gallons needed} = \frac{150.75}{25} = 6.03 \text{ gallons}
\]

### Steps to Solve Problems:
1. **Identify the Numbers**: Read the problem carefully and determine what decimal numbers are involved.
2. **Determine the Operation**: Decide whether you need to add or subtract based on the context (finding total cost, remaining balance, etc.).
3. **Align the Decimals**: For addition and subtraction, line up the decimal points.
4. **Perform the Calculation**: Execute the operation carefully, making sure to carry over values when necessary for addition or borrowing for subtraction.
5. **Check Your Work**: Verify the result to ensure accuracy.

Using these methods, decimal operations can help you solve daily life problems more effectively and make informed decisions.