First distribute the -2 so the x is a term on its own:
y - 5 = - 2(x+6) --> y - 5 = -2x -12
Now, standard form satisfies the equation ax + by = c. Thus, x and y must be isolated on one side with the constant on the other.
y - 5 = -2x - 12
y = -2x -7
2x + y = -7
