Can you connect all nine dots with only four straight line segments without losing contact with the paper while drawing?

Correct the equation above by inserting one straight line.

Bob and John form a team together. Bob is as old as John will be when Bob is twice as old as John was when Bob was half as old as the sum of their current ages. John is as old as Bob was when John was half as old as he will become over ten years.

How old are Bob and John?