Table Rule Help Me

What is the rule if x is 6 and y is 7. Then x is 5 and y is 5.

Table

IN(X)      6    5    4    3      2      1        0

OUT(Y)  7    5    3     1     -1     -3      -5

arithmetical sequence:

$\begin{array}{|rcll|} \hline a_n &=& a_1 + (n-1)\cdot d \quad & | \quad d = +2 \qquad a_1 = -3 \\ a_n &=& -3 + (n-1)\cdot 2 \\ a_n &=& -3 + 2n-2 \\ \mathbf{a_n} &\mathbf{=}& \mathbf{-5 + 2n} \quad & | \quad n = IN(X) \qquad a_n = OUT(Y) \\\\ \mathbf{OUT(Y)} &\mathbf{=}& \mathbf{-5 + 2\cdot IN(X)} \\ \hline \end{array}$