Find the n-th term and the sum (Sn) for the arithmetic sequence 6, 10, 14, 18, ...

The first term is $a_1 = 6$.
The common difference $d$ is found by subtracting any term from its succeeding term:
$d = 10 - 6 = 4$
$d = 14 - 10 = 4$
So, the common difference is $d = 4$.

The formula for the $n$-th term of an arithmetic sequence is:

Substitute $a_1 = 6$ and $d = 4$:

The $n$-th term is $\boxed{4n + 2}$.

The formula for the sum of the first $n$ terms of an arithmetic sequence is:

Substitute $a_1 = 6$ and $d = 4$:

Factor out 2 from $(4n+8)$:

The sum of the first $n$ terms is $\boxed{2n^2 + 4n}$.