Gst on hotel rooms

I am a hotel owner in Agra. One small question is whether GST percentage is applicable on Room Rent or on Net amount received from customer.

Example: I received a booking through Goibibo for which I am getting Rs. 2450/- Room Rent + GST.

Now do I need to pay 12% GST on this as my Room Rent is below Rs. 2500/- i.e. Rs. 2450/- (Range between Rs. 1000/- to Rs. 2500/- GST is 12%) or 18% GST, as my Net Amount of this room will be Rs. 2500/- plus including GST (Range between Rs. 2500/- to Rs. 7500/- GST is 18%).

Thanks