18. What conditions must be true for Ax^2? + Cy^2 + Dx + Ey = 0, so that the conic section is a parabola with vertex (0,0) and horizontal axis of symmetry?

Mrs. morton has a special reward system for her class. when all her students behave well, she rewards them by putting 3 marbles into a marble jar. when the jar has 100 or more marbles, the students have a party. right now, the the jar has 24 marbles. how could mrs. morton reward the class in order for the students to have a party?