A dealer sold two cell phones, he got `20%` profit on one and `20%` loss on the other. If the cost price of each cell phone is Rs. 20000, then find the profit or loss percentage.

Explanation

To solve the problem step by step, we need to calculate the selling prices of both cell phones based on the given profit and loss percentages and then determine the overall profit or loss percentage.

### Step 1: Calculate the Selling Price of the First Cell Phone
- Cost Price (CP) of the first cell phone = Rs. 20,000
- Profit = 20%
- Selling Price (SP) can be calculated using the formula:
\[ SP = CP + (Profit \% \times CP) \]
\[ SP = 20,000 + (20\% \times 20,000) \]
\[ SP = 20,000 + (0.20 \times 20,000) = 20,000 + 4,000 = 24,000 \]

### Step 2: Calculate the Selling Price of the Second Cell Phone
- Cost Price (CP) of the second cell phone = Rs. 20,000
- Loss = 20%
- Selling Price (SP) can be calculated using the formula:
\[ SP = CP - (Loss \% \times CP) \]
\[ SP = 20,000 - (20\% \times 20,000) \]
\[ SP = 20,000 - (0.20 \times 20,000) = 20,000 - 4,000 = 16,000 \]

### Step 3: Calculate Total Cost Price and Total Selling Price
- Total Cost Price of both cell phones:
\[ Total \, CP = 20,000 + 20,000 = 40,000 \]
- Total Selling Price of both cell phones:
\[ Total \, SP = 24,000 + 16,000 = 40,000 \]

### Step 4: Calculate Overall Profit or Loss
- Overall Profit or Loss = Total SP - Total CP
\[ Overall \, Profit/Loss = 40,000 - 40,000 = 0 \]

### Step 5: Calculate Profit or Loss Percentage
Since there is no overall profit or loss:
- Profit or Loss Percentage = \(\frac{Overall \, Profit/Loss}{Total \, CP} \times 100\)
\[ Profit/Loss \, Percentage = \frac{0}{40,000} \times 100 = 0\% \]

### Final Answer
The overall profit or loss percentage is **0%**.

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