Alright, lets get started.
Rent for a 3-bedroom apartment per month = $ 936
So, rent for this apartment for a year = 
Once we sign 12-month lease, the offer comes with it is, one month rent free.
So, we need to subtract one month rent from $ 11232
So, new rent for 12 month after apply lease = 
So, $ 10296 will be for 1 year lease amount.
So, for monthly lease amount = 
So, $ 858 is our new monthly amount. : Answer
Hope it will help :)