can you combine 2 short speaker wires into 1 long one

[Alfredo1]

i have a speaker 20 feet away from my tv and its already hooked up to the wire and receiver
i want to place it farther away...to like 30 feet and i got an 15 feet of extra wire in my garage
can i combine them both and will it still work...or do i need to buy a new speaker wire???