A shopkeeper bought 100 pens at Rs 10 each. He sold 60 pens at 20% profit and the rest at 10% loss.

Cost price of 1 pen = Rs 10
Number of pens = 100
Total cost price = $100 \times 10 = 1000$

60 pens sold at 20% profit:
Selling price per pen = $10 + 20% \text{ of } 10 = 10 + 2 = 12$
Total selling price = $60 \times 12 = 720$

40 pens sold at 10% loss:
Selling price per pen = $10 - 10% \text{ of } 10 = 10 - 1 = 9$
Total selling price = $40 \times 9 = 360$

Total selling price = 720 + 360 = 1080

Profit = Total SP - Total CP = 1080 - 1000 = 80

Overall profit percentage = $\frac{80}{1000} \times 100 = 8%$

✅ Answer: 8% profit