Solve
6 + 7 + 8 + 9 + 11 = ?

Assuming below equations are true.
1 + 2 + 3 + 4 + 5 = 4
4 + 5 + 6 + 7 + 8 = 3


3

1 + 2 + 3 + 4 + 5 => 15 => 5 - 1 => 4
4 + 5 + 6 + 7 + 8 => 30 => 3 - 0 => 3
6 + 7 + 8 + 9 + 11 => 41 => 4- 1 => 3