An online electronics store bought 20 keyboards and 15 phone chargers for $130 and then sold each keyboard for $30 and each phone charger for $15.

Part A: Which expression represents the amount of money the store made? (1 point)
(20)(30) + (15)(15) − 130
(20)(15) + (15)(30) − 130
(20)(30) + (15)(15) + 130
(20)(15) + (15)(30) + 130

Part B: Explain why your answer to Part A is correct. (1 point)

Part C: What is the value of the expression you chose in Part A? Show each step of your work. (2 points)

Let’s solve each part step-by-step.

### Part A: Identifying the Correct Expression
The store bought 20 keyboards and 15 chargers for a total cost of $130. Afterward, they sold:
- Each keyboard for $30, so total revenue from keyboards is $20 \times 30$.
- Each phone charger for $15, so total revenue from chargers is $15 \times 15$.

To find the store's profit (money made), we calculate the total revenue and then subtract the initial cost of $130:
\[
(20 \times 30) + (15 \times 15) - 130
\]

So, the correct answer is:
\[
(20)(30) + (15)(15) - 130
\]

### Part B: Explanation
This expression is correct because it calculates the store’s profit by:
1. Adding the revenue from selling 20 keyboards at $30 each: $20 \times 30$.
2. Adding the revenue from selling 15 chargers at $15 each: $15 \times 15$.
3. Subtracting the initial cost of $130, which represents the amount the store spent to buy the items.

This gives the total money the store made as profit after covering the initial expenses.

### Part C: Calculating the Value of the Expression
Now we evaluate the expression step-by-step:

1. Calculate revenue from keyboards:
   \[
   20 \times 30 = 600
   \]
2. Calculate revenue from chargers:
   \[
   15 \times 15 = 225
   \]
3. Add these revenues:
   \[
   600 + 225 = 825
   \]
4. Subtract the initial cost of $130:
   \[
   825 - 130 = 695
   \]

So, the value of the expression is **$695**.

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Let me know if you'd like further details or have questions about any part of this solution.

### Related Questions
1. What would the profit be if the store sold each keyboard for $25 instead of $30?
2. How would the store’s profit change if they had bought 25 keyboards and 10 chargers instead?
3. If the store had received a discount and paid only $100 for all items, what would the new profit be?
4. What is the percentage profit made by the store based on the initial cost?
5. How many additional keyboards would need to be sold to increase profit by another $100?

### Tip
To find profit, always calculate total revenue first and then subtract any initial costs.

Solve a profit calculation problem for an electronics store buying keyboards and chargers. Learn to use expressions for calculating total revenue and profit. Suitable for Grades 6-8.

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