I could get 2 /29s or
4 /30's, or 8 /31's
maybe I'm reading to deep into the question.
You're right if you interpret what the OP said literally, but given he gave us the answer, we knew technically how he posited the question was incorrect. I imagine the original question was something like:
How many /28 hosts and subnets can you get out of 192.168.5.0 assuming classful boundaries?
or it would have been nice for them to just say:
How many /28 hosts and subnets can you get out of 192.168.5.0/24?