rental income

you first need to calculate the total gross rent received during the year . from his deduct thek amount of municipal taxes paid.
on the balance you get 30%flat standard deduction towards the expenses incurred for maintenance of flat. also if there's any home loan taken you can claim deduction for interest paid upto 2lacs. balance will by your income from house property to be offered for tax

can we show rental income after deducting maintanance amount and how?

- No...

We can't avail maintenance expenses separately in the rental income.

But, We can get 30% standard deduction on rental income and also get deduction for the Municipality Tax amount.
No way for other claims...

30% deduction is for that purpose only to cover maintainance and other expense in ur case not allowed compute according to it Act 1961