Complimentary Strand & mRNA Strand?

The complimentary strand is pretty simple - A pairs with T, and G pairs with C. So wherever you see a C it's complimentary base will be a G on the other strand.

So complimentary strand would be: GCA GAG AAG GTG

mRNA is basically the same as above, however it uses U instead of T. To G and C pair the same, but now U pairs with A (the base changes here cause of protein synthesis).

So mRNA strand would be: GCA GAG AAG CCU GUG