Tip of Tip ( A and B )

checksys

In my game. you can see a tip in the screen top.
What about it ?!

level one Tip: a == b
solution like this: 1-2 2-3 3-4 4-5

level two Tip: ( a == b + 2 or b == a + 2 )
solution like this: 1-2 4-5 3-1 3-6

level three Tip: ( a + b == 5 or a + b == 10 )
solution like this: 1-2 3-0 5-4 6-2

level four Tip: ( a == b * 2 or b == a * 2)
solution like this: 1-2 4-3 6-1 2-5

Have you any interesting suggest about level five ??