Answer
There are no common solutions.
Work Step by Step
$2x+8y=12$
$x=-4y$
Substitute -4y for x in the first equation.
$2(-4y)+8y=12\longrightarrow$ simplify
$-8y+8y=12\longrightarrow$ simplify
$0=12$
Since this is a false statement, there are no common solutions for the 2 equations.