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: the h . c . f . of two numbers is 15 and their l . c . m . is 420 . if one of the numbers is 375 , then the other is :
16.8
100