Description: This example of combining like terms in an expression get a little hairy. Listen closely. Created by Sal Khan. And there will be a temptation, because you see a y here and a y here to say, oh, maybe I can add this negative 3y plus this 4xy somehow since I see a y and a y. So first, let's think about the y terms. So we have plus 4xy right over here.*Teacher Advisor is 100% free.