What is the value of the obligatory Zakat for a working man and his wife who own land, a shop, and have three children?

The question is vague, but generally, if each of you possesses the value of a nisab (85 grams of gold) and a year has passed on it, then zakat is obligatory upon everyone. If the land is prepared for trade, it is added to the rest of the assets, and whoever does not possess a nisab is not obligated to pay zakat. As for the shop, zakat is only obligatory on its rent. So, whoever's share reaches the nisab by adding the land or trade goods, zakat becomes obligatory upon him. If what is meant is the trade goods inside the shop, then they are appraised, and zakat is obligatory upon whoever's assets, by adding these goods to other wealth, reach the nisab.