IP address: 172.16.12.0
Subnet Mask: 255.255.255.0

There must be 14 host and the 5th subnet must be used. I believe I have figured the answer I just want to make sure it is correct.

I have the 5th subnet as being 172.16.12.64 with a subnet mask of 255.255.255.240 a broadcast of 172.16.12.79 and a range of 172.16.12.65 - 172.16.12.78.