So we add up the two half reactions by first adding up all the molecules on this side and then add up all the molecules on this side. So zinc solid plus acreage copper plus two electrons gives us this produces everything on this side. So zinc or acreage zinc plus copper solid plus our two electrons. Now, notice one thing. That two electrons up here on this side and on this side. And that means by using simple algebra we just cross these guys out, we subtract two e, and what we get is our final net reaction.