Let's calculate the effective price Rahim paid per book at each store, including discounts, deals, taxes, and fees.

**Store A:**
- Original total: Rs. 1,600
- Discount: 15% of Rs. 1,600 = Rs. 240
- Discounted total: Rs. 1,600 - Rs. 240 = Rs. 1,360
- Sales tax: 5% of Rs. 1,360 = Rs. 68
- Final total: Rs. 1,360 + Rs. 68 = Rs. 1,428
- Number of books: 25
- Price per book: Rs. 1,428 / 25 = Rs. 57.12

**Store B:**
- Original total: Rs. 3,200
- Deal: Buy 3, get 1 free, so for 35 books, he effectively pays for 35 - (35/4) = 35 - 8.75 = 26.25 books
- Price per book: Rs. 3,200 / 26.25 ≈ Rs. 121.90

**Store C:**
- Original total: Rs. 3,800
- Discount: 10% on every 10th book, so 4 books get a discount. 10% of the price of 4 books = 0.10 * (4 * (Rs. 3,800 / 40)) = Rs. 38
- Discounted total: Rs. 3,800 - Rs. 38 = Rs. 3,762
- Service charge: 7% of Rs. 3,762 = Rs. 263.34
- Final total: Rs. 3,762 + Rs. 263.34 = Rs. 4,025.34
- Number of books: 40
- Price per book: Rs. 4,025.34 / 40 = Rs. 100.63

**Store D:**
- Original total: Rs. 2,400
- Discount: 50% off on 1 book = 0.50 * (Rs. 2,400 / 30) = Rs. 40
- Discounted total: Rs. 2,400 - Rs. 40 = Rs. 2,360
- Sales tax: 6% of Rs. 2,360 = Rs. 141.60
- Final total: Rs. 2,360 + Rs. 141.60 = Rs. 2,501.60
- Number of books: 30
- Price per book: Rs. 2,501.60 / 30 = Rs. 83.39

**Store E:**
- Original total: Rs. 1,800
- Discount: 8% of Rs. 1,800 = Rs. 144
- Discounted total: Rs. 1,800 - Rs. 144 = Rs. 1,656
- Additional fee: 4% of Rs. 1,656 = Rs. 66.24
- Final total: Rs. 1,656 + Rs. 66.24 = Rs. 1,722.24
- Number of books: 20
- Price per book: Rs. 1,722.24 / 20 = Rs. 86.11

Now, let's calculate the average price per book across all stores:

Total books bought: 25 + 35 + 40 + 30 + 20 = 150 books
Total amount paid: Rs. 1,428 + Rs. 3,200 + Rs. 4,025.34 + Rs. 2,501.60 + Rs. 1,722.24 = Rs. 12,877.18

Average price per book: Rs. 12,877.18 / 150 ≈ Rs. 85.85

Rahim paid an average of approximately Rs. 85.85 per book.
할인, 거래, 세금 및 수수료를 포함하여 각 매장에서 라힘이 책당 지불한 실제 가격을 계산해 보겠습니다.

**스토어 A:**
- 원래 총액: Rs. 1,600
- 할인: 1,600의 15% = Rs. 240
- 할인 총액: Rs. 1,600 - Rs. 240 = Rs. 1,360
- 판매세: 1,360의 5% = Rs. 68
- 최종 총액: Rs. 1,360 + Rs. 68 = Rs. 1,428
- 책 수: 25
- 책당 가격: Rs. 1,428 / 25 = Rs. 57.12

**스토어 B:**
- 원래 총액: Rs. 3,200
- 거래: 3권을 구매하면 1권을 무료로 제공하므로 35권을 구매할 경우 35권 - (35/4) = 35권 - 8.75권 = 26.25권을 구매할 수 있습니다.
- 책당 가격: Rs. 3,200 / 26.25 ≈ Rs. 121.90

**스토어 C:**
- 원래 총액: Rs. 3,800
- 할인: 10번째 책마다 10% 할인, 따라서 4권의 책이 할인됩니다. 4권의 가격의 10% = 0.10 * (4 * (Rs. 3,800 / 40)) = Rs. 38
- 할인 총액: Rs. 3,800 - Rs. 38 = Rs. 3,762
- 서비스 요금: Rs. 3,762의 7% = Rs. 263.34
- 최종 총액: Rs. 3,762 + Rs. 263.34 = Rs. 4,025.34
- 책 수: 40
- 책당 가격: Rs. 4,025.34 / 40 = Rs. 100.63

**스토어 D:**
- 원래 총액: Rs. 2,400
- 할인: 1권 50% 할인 = 0.50 * (Rs. 2,400 / 30) = Rs. 40
- 할인 총액: Rs. 2,400 - Rs. 40 = Rs. 2,360
- 판매세: 2,360의 6% = Rs. 141.60
- 최종 총액: Rs. 2,360 + Rs. 141.60 = Rs. 2,501.60
- 책 수: 30
- 책당 가격: Rs. 2,501.60 / 30 = Rs. 83.39

**스토어 E:**
- 원래 총액: Rs. 1,800
- 할인: Rs. 1,800의 8% = Rs. 144
- 할인 총액: Rs. 1,800 - Rs. 144 = Rs. 1,656
- 추가 요금: Rs. 1,656의 4% = Rs. 66.24
- 최종 총액: Rs. 1,656 + Rs. 66.24 = Rs. 1,722.24
- 책 수: 20
- 책당 가격: Rs. 1,722.24 / 20 = Rs. 86.11

이제 모든 스토어의 책당 평균 가격을 계산해 보겠습니다:

구매한 총 책 수: 25 + 35 + 40 + 30 + 20 = 150권
총 지불 금액: Rs. 1,428 + Rs. 3,200 + Rs. 4,025.34 + Rs. 2,501.60 + Rs. 1,722.24 = Rs. 12,877.18

책당 평균 가격: Rs. 12,877.18 / 150 ≈ Rs. 85.85

라힘은 책당 평균 약 Rs. 85.85를 지불했습니다.