Let’s break it clearly.
Understand the scheme
“Buy 25, get 5 free” ⇒ total notebooks given = 30
So, for every 30 notebooks, customer pays for 25.
Selling price (as per claim)
He claims CP = ₹10, so SP = ₹10 per notebook
Amount paid by customer = (25 \times 10 = ₹250)
Actual cost
Actual CP = ₹5 per notebook
Total cost for 30 notebooks = (30 \times 5 = ₹150)
Profit
Profit = (250 - 150 = ₹100)
Profit % =
150100×100=66.67%=6632%
Discount %
Free 5 on 25 ⇒
305×100=16.67%=1632%
Difference
6632−1632=50%
Final Answer:
50%