Let, the cost price of the goods is 100 Tk.
By this 100 Tk. he actually bought goods @ 15% profit = (100+15% of 100) Tk. = 100+15=115 tk.
At 10% loss,
Selling price of the goods be= (115-10% Tk.
His overall gain = 103.5-100=3.5 Tk.
When gain is 3.5 Tk. Cost price =
ans. Real cost of the goods is 100,000 TK.