How is zakat calculated on money that includes a residential apartment, rented apartments and shops, unfinished apartments, a summer apartment used one month a year and on which installments are due, in addition to a sum of money in an Islamic bank from which monthly withdrawals are made to meet needs?

There is no zakat on the apartment you live in, nor on the value of rented properties such as the apartment and the two shops. Zakat is only obligatory on their income if it reaches the nisab and a full year has passed over it. Similarly, there is no zakat on the value of an apartment designated for summer residence. As for money that reaches the nisab and a full year passes over it, zakat is obligatory on it at a rate of 2.5%. The debts you owe are not deducted from the zakatable money as long as you have surplus wealth beyond your needs that can cover these debts.