Question 748164
We know that two lines are parallel if they have the same slope (and they are distinct). When the lines are in general form we'll use the formula m=-B/A to find their slopes with

{{{
Ax+By=C
}}}

{{{
9x+3y=12
}}}
{{{
27x+9y=40
}}}



first line: m=-3/9=-1/3

second line: m=-9/27=-1/3


these lines have the same slope and since we know that they are not the same line because

{{{

A[1]/A[2] <> C[1]/C[2]
}}}



they must be parallel


:)