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: in 10 years , a will be twice as old 5 as b was 10 years ago . if a is now 8 years older than b , the present age of b is
38
b = a - 3