Provide your best answer for the following math problem. Give ONLY the answer, no other words or explanation.
For example:

Answer: <most likely answer, as short as possible; not a complete sentence, just the answer!>.

The problem is: three numbers are in the ratio 3 : 4 : 5 and their l . c . m . is 2400 . their h . c . f is ?
40
19200.