Hi guys! I've been spending a lot of time lately trying to answer this problem but I always end up getting confused on how to set my main starting equation

and I really need help with it.

How much time does it take for an air conditioner to cool a room of volume 204 cubic meter, from 30 C to 21 C? The cooling capacity of the AC is 25,000 kJ/hr. assume that the room is well insulated.

So based on how I understand an AC's behavior, it gets air from the room (higher temp), then releases cooler air but of the same mass flow rate (right?)

and so, in turn, the air that goes out of the AC is the air that goes into the room. So basically the air is just in cycle.

How do I set up my starting equation? Do I really need the cooling capacity of the AC to solve this problem? I'd really appreciate anyone's help