This question you just need to manipulate the equation, in a way the "m" is written as a function of n.
We start with the initial equation:
m + 1 = -2(n + 6)
This is pretty much given already. You just need to subtract "1" from both sides, and you'll get your "m" as a function of "n"
m(n) = -2(n+6) - 1
Rearranging:
m = -2n - 13
