How is the due zakat calculated on an amount of 18,000 pounds, the origin of which was 1,000 pounds invested by the mother in sheep in 1997, taking into consideration the difference in the value of the Egyptian pound between 1997 and 2009 and the current time, and is it obligatory to pay zakat from the capital itself or from other money?

The nisab (minimum threshold for zakat) is approximately 85 grams of gold or 595 grams of silver. Once wealth reaches this nisab and a full lunar year (hawl) passes, zakat becomes obligatory. If the mother sinned by delaying the payment of zakat, then what was due from her must be paid. If the wealth reached the nisab on its own or when combined with trade goods, zakat became obligatory on it. If it is not known when the wealth reached the nisab, the person who was trading with the wealth should be asked, or an investigation should be conducted to clear one's conscience.

After the mother's death, the wealth became an inheritance (tarakah), and each heir must pay zakat on their share if it reached the nisab. If an heir purchased something with it on which zakat is not obligatory, then there is no zakat due on that purchase, but they must pay what was due in zakat for the previous years. Zakat is not paid from the specific item itself, but from its kind. The zakat on trade goods is paid in money, and what was due at the time of obligation must be paid according to its value at the time of obligation.