I start doing the first two questions that you assigned. When I get to #4, it says (a, b). I figured it was doing the same thing I did for #2, just with the #4 equations. But then when I get to #10, it says (a). I start getting confused because problems 9-12, it's about Graphing the equations. I try looking in the answer key to see what it meant by doing (a), but I find that there were no a's or b's assigned for problems 3-14. So is this just a typo error or does this mean something else?