If an employee's basic salary is Rs 35,000, then the HRA received according to the city division will be something like this.
1) 27% of Rs 35,000 i.e. Rs 9,450 for X category cities.
2) 18% of Rs 35,000 i.e. Rs 6,300 for Y category cities.
3) Rs 3150 for Z category cities i.e. 9% of Rs 35,000.