We know that 1 kg = 1000 grams.
Here, she has to sell 4 kg i.e., 4000 grams of silver.
Cost of 1 gm of silver = ₹ 20.25.
∴ The cost of 4000 grams of gold = 20.25 × 4000 = 2025100×4000
= ₹ 81000