1. The problem statement, all variables and given/known data Find symmetric equations for the line of intersection of the planes 2. Relevant equations 5x - 2y - 2z = 1 4x + y + z = 6 3. The attempt at a solution I interpret this problem to say that I need to find a line of intersection of the two planes. I think I add them together and get 9x -y -z = 7. After which, I need to find symmetric equations of that line and I think that is what I am having trouble with. I would like a little background into what a symmetric equation is. The book says that I need to first find a parametric equation then solve for t. Thanks!