Trade-in in Liu Fu means that the gold price of that day is reduced by 20, then multiplied by your old weight and then multiplied by the discount. Discount means: If you are not the gold in Liu Fu, you need to check the quality of the gold for you, and then make sure to give you a 7-8 discount. This will convert your old gold price, and then you can choose another piece of jewelry and calculate the price, so you can make up the difference. If your old gold is Liu Fu, you don't need to multiply it by the discount.