What is the value of the Zakat due on the remaining amount after the aforementioned series of financial transactions?

Zakat should be calculated according to the lunar year. If the land was purchased for construction, there is no Zakat on it. However, if it was for trade, then Zakat on trade goods applies. There is no Zakat on the amount spent on the wife's medical treatment. As for the remaining portion of the land's price, Zakat is due on it if it reaches the nisab (minimum threshold) and a hawl (full lunar year) has passed on it. Its hawl begins from the day the land was sold. The nisab is equivalent to 85 grams of gold or 595 grams of silver, and a quarter of one-tenth (2.5%) is obligatory to be given out. As for salary amounts, each can be subject to Zakat individually, or all of them can be subject to Zakat when the hawl of the first amount you possessed is due. The amount that represents the price of the gold piece, if it belongs to the wife, has its own independent hawl, and Zakat becomes due on it if its hawl passes and it reached the nisab before being spent on construction.