A man bought a book for Rs 100 and sold it for Rs 180. Find his profit (or) loss percentage.

Answer

To solve the problem of finding the profit percentage when a man bought a book for Rs 100 and sold it for Rs 180, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Cost Price (CP) and Selling Price (SP)**:
- Cost Price (CP) = Rs 100
- Selling Price (SP) = Rs 180

2. **Determine if there is a Profit or Loss**:
- Since the Selling Price (SP) is greater than the Cost Price (CP), there is a profit.

3. **Calculate the Profit**:
- Profit = Selling Price - Cost Price
- Profit = SP - CP
- Profit = 180 - 100
- Profit = Rs 80

4. **Calculate the Profit Percentage**:
- The formula for Profit Percentage is:
\[ \text{Profit Percentage} = \left( \frac{\text{Profit}}{\text{Cost Price}} \right) \times 100 \]
- Substituting the values:
\[ \text{Profit Percentage} = \left( \frac{80}{100} \right) \times 100 \]
- Simplifying:
\[ \text{Profit Percentage} = 0.8 \times 100 = 80\% \]

5. **Conclusion**:
- The profit percentage is 80%.