If a parabola opens downwards and has a maximum, and if it has a vertex of (-2,-3) and a y-intercept of (0,-11), what is the axis of symmetry, and what is the maximum value of the function?

If a parabola opens downwards and has a maximum and if it has a vertex of 23 and a yintercept of 011 what is the axis of symmetry and what is the maximum value class=