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: john is 3 times as old as sam . if john will be twice as old as sam in 9 years , how old was sam two years ago ?
7
Sam was 6 years old two years ago.