How do I verify that the following is a subspace of V?

w=(x,y,2x-3y), x and y are real numbers. V=R^3

I am stuck at how to set it up. This is what I think.

(x,y,2x-3y)+?=

I don't know what to add. I know that if w=(x,x1,x2), I can add that too (y,y1,y2). But what about (x,y,2x-3y)? Please help on how to set it up. Thank you